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    Have a question about solid state relays and their applications? Ask me!

    PeteB

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      Pete Bamburak

       

      Pete Bamburak

      As the Field Applications Sales Engineer for Crydom North America, Pete offers 26 years of expertise and experience in solid state relay use and applications.


       

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        • 1. Re: Have a question about solid state relays and their applications? Ask me!
          kobehua

          To Pete,


          Hi i am a student from UTHM Malaysia currently i am doing a degree electrical and electronic research, so i might want to ask sir technically about solid state relay first is about the Switching Mode of the Solid State Relay. There are 5 types as shown in the Element14. so can Sir practically about all those type of mode in application uses?

           

          Such as:

          1) AC Switch

          2) DC Switch

          3) Non-zero crossing

          4) Random Turn On

          5) Zero Crossing

           

          i don't know which type suitable to my research product Mr Pete, but i prefer a switching mode that are able to response instantly to OFF the AC terminal when detect a low voltage signal on the DC terminal. Please let me know if Mr Pete have any ideas which type of switching mode relevant or suitable to my research...

           

          Thanks and regard,

          Vincent Lee

          2 of 2 people found this helpful
          • 2. Re: Have a question about solid state relays and their applications? Ask me!
            PeteB

            Hello Vincent, and thank you for your question.

             

            I'll do my best to answer it as completely as possible here, but for more detailed explanations you can access anytime, Crydom provides thorough explanations of what solid state relays are, how they're used, the selection of which types to use, how to determine heatsinking requirements, etc., etc., under the "Tech Library" and "Service and Support" heading on our Crydom Website home page, www.crydom.com   Links to the Service and Tech Library are:

             

            http://www.crydom.com/en/Service/Training.shtml

            http://www.crydom.com/en/Tech/Tips.shtml

             

            So to your questions...

             

            #1 and #2 pertain to the 2 general types of SSR's.   Unlike mechanical relays, solid state relays are specificly constructed to switch either AC loads or DC loads.  They cannot switch both.   SSR's that switch AC loads typically use dual power SCR's, (Silicon Controlled Rectifiers), connected inversely and in parallel,  with each SCR switching one side of the AC voltage.   DC switching SSR's utilize Bi-polar power transistors or more commonly power MOSFET devices.   Again, more details on this subject can be obtained through the links provided.

             

            #3, #4, and #5 refer to the switching characteristics available with solid state relays.   The terms "Non-zero crossing"  and "Random turn-on" are interchangeable and mean exactly the same thing.     Since solid state relays are of course, "solid state", and can react in micro seconds if desired unlike mechanical relays,  the exact switching point in the AC waveform where the output turns on can be easily designed into the SSR.     The main advantage of using a zero-crossing turn on SSR is when the load being switched tends to be of a "high inrush" type, usually having a capacitive  characteristic or a tungsten lamp load where the "cold resistance" of a tungsten filament is much lower than its "hot resistance" and would result in a very large current surge for the first few AC cycles.  The turn-on at the zero voltage crossing point lessens that surge substantially.    The zero-cross effect means that if the input signal is applied at any point during the AC output wave other than very close to the zero voltage point of that wave, the output will "wait" to switch on until the AC wave reaches the following zero point.    The "random switching" type SSR means that the output switches on within micro-seconds of the application of the input regardless of where the AC waveform is at that point.   Random turn-on type SSR's are typically recommended for inductive load applications such as motors, coils, etc, due to factors involving the current and voltage phase shift involed,  ( a much deeper subject than can be covered here), along with applications that use the SSR to vary the power levels of AC loads through "phase angle control" such as lamp dimming or resistive heater control.  

             

            The last part of your question regarding a need to "instantly" turn-off your AC output when a low level DC input is received can be covered in two parts.

             

            First, the turn-OFF of either a zero-crossing or random turn-on SSR are both identical.   Since the output uses SCR's, even if an input signal commands a turn-on the SCR that is conducting at that time will NOT stop conducting until the load current is reduced to zero, (for a resistive load that point will be at the zero-voltage point of the AC wave).   Therefore, the turn-off time for an AC output SSR can be almost as long as 1/2 the AC cycle time, (for 50 hz that would be 10msec), or as short as a few micro seconds if the turn-off was received just at the zero-cross point.

             

            The second part of your last question involves your need to turn-off the load when a DC signal is received.  This requires a "normally closed" SSR function (output always on without an input signal,   output will switch off with an input signal, sometimes referred to as a form "B" switch).   Just about 99.99% of the SSR'[s manufactured in the world are of the normally open type.   Fortunately, Crydom covers that 00.01% with a solid state series of relays that includes some normally closed (for "B") versions.   Please look through the datasheet for our S1 series (link below) where you will see that for most of the variations listed a "-B" suffix can be added that designates a normally closed version.

             

            http://www.crydom.com/en/Products/Catalog/s_1.pdf

             

            I hope this "small" dissertation has helped you in your understanding of the Crydom solid state relays.

             

            Thank you again,

            Pete B.

            3 of 3 people found this helpful
            • 3. Re: Have a question about solid state relays and their applications? Ask me!
              PeteB

              Vincent.   I would also like to add that there is a very comprehensive set of "Crydom Solid Statement" paers covering almost every facet of the Crydom SSR's and their application in our "Documents" section here in Element 14.

               

              http://www.element14.com/community/community/suppliers/crydom

               

              It would be very useful for you to take a look at the subjects covered which include our discussion.

               

              Regards,

              Pete B.

              3 of 3 people found this helpful
              • 4. Re: Have a question about solid state relays and their applications? Ask me!
                kobehua

                Sir Pete, thank for the information given above. your guidance is very professional and technical....

                 

                however i would like to ask more questions about the as below:

                 

                Relay Terminals

                Cage Clamp

                Push In

                Surface Mount

                Through Hole

                 

                Contact Configuration

                SPST

                SPST-NC

                SPST-NO

                 

                MSL

                     MSL 2A - 4 weeks

                 

                SVHC

                No SVHC (15-Dec-2010)

                No SVHC (19-Dec-2011)

                No SVHC (20-Jun-2011)

                 

                these are the parameter when choosing the solid state relay property at

                http://my.element14.com/jsp/search/browse.jsp?N=2105+204034&Ntk=gensearch&Ntt=solid+state+relay&Ntx=mode+matchallpartial

                 

                i am not very clear about these parameters when selecting the SSR, so i would like to ask Sir Pete for more simple and technical explaination...sorry for any trouble that i causes to you Sir.

                 

                thank and regard

                Vincent Lee

                1 of 1 people found this helpful
                • 5. Re: Have a question about solid state relays and their applications? Ask me!
                  PeteB

                  Hello Vincent.  Glad to help.

                   

                  The parameter shown as "MSL" refers to "Moisture Sensitivity Level".  Certain solid state components require special attention regarding exposure to ambient atmosphere.  You can refer to the WIkipedia link here that has a decent explanation.

                   

                  http://en.wikipedia.org/wiki/Moisture_Sensitivity_Level

                   

                  The term "SVHC" regards products that meet the "REACH" European Community hazardous material regulations that were effective as of the date shown.  Selection of the "No SVHC (19-Dec-2011)" box will show all the products that have no restrictions for hazardous substances per the latest list published.

                   

                  "Contact Configuration" is simply that.  It allows the selection of the available output contact configurations available for the particular category.  In this case, it appears you've selected "PCB Mount" type relays, and within that category there are only two types available, SPST-NO, (single pole normally open)  and SPST-NC, (single pole normally closed).  The selection of just the SPST selection would show all the SPST products, both NO and NC.

                   

                  The "Relay Terminals" selection just comes down to your preference as to how to connect to or attach wires to the relays.  If you are undecided, the best thing to do would be to examine a couple of datasheets and look at the differences.

                   

                  Pete B.

                  1 of 1 people found this helpful
                  • 6. Re: Have a question about solid state relays and their applications? Ask me!
                    kobehua

                    Mr Pete,

                    ok....thank Mr Pete

                     

                    so what is the different between SPST-NO, (single pole normally open and SPST-NC, (single pole normally closed)? sorry i cant found any relevant of this details on wiki or other sources. and again i would like to ask Mr Pete about this.

                    1 of 1 people found this helpful
                    • 7. Re: Have a question about solid state relays and their applications? Ask me!
                      PeteB

                      Vincent.  

                       

                      The terms SPST-NO and SPST-NC are probably the most basic terms in referring to a switch operation.  "SPST" refers to a "S"ingle "P"ole, (one set of switch contacts that have only one action, ("S"ingle "T"hrow, meaning either open or closed).       NO,   "Normally open"  means just that.  Without an input signal, the contacts are normally "Open".  (In the case of a solid state relay, the output is "OFF").      When an input signal is applied, the contacts then "Close"

                       

                      NC-  :"Normally closed" is the opposite.   Without an input signal, the contacts are "closed".  When an input signal is applied, the contacts move to the "Open" position.

                       

                      There are many references you should be able to find on the internet to diagram and explain this in much detail.  Search for "basic light switch wiring"  or "basic electrical switch wiring".

                       

                      Pete B.

                      1 of 1 people found this helpful
                      • 8. Re: Have a question about solid state relays and their applications? Ask me!
                        kobehua

                        thanks Mr Pete,

                         

                        a very last question....the Load Current of the SSR mean the

                         

                        1)The SSR maximum load current of 12A which is in range 0-12A allow to load?


                        or


                        2)the SSR can allow only 12A current to the load?

                         

                        Regard

                        Vincent Lee

                        1 of 1 people found this helpful
                        • 9. Re: Have a question about solid state relays and their applications? Ask me!
                          PeteB

                          Vincent,

                           

                          The maximum load current rating of the SSR refers to the maximum load current that can be safely handled by the SSR, and is the top of a range.   It can switch loads that vary from the minimum specifiied load current, (also noted on the SSR datasheet), to that maximum.  (Your statement #1).

                           

                          The relay WILL NOT limit the load current, and if a load draws more current than the specified maximum, the SSR could be permanently damaged.

                           

                          Regards,

                          Pete B.

                          1 of 1 people found this helpful
                          • 10. Re: Have a question about solid state relays and their applications? Ask me!
                            ehagerman2

                            What kind of SSR do I need for this application?  Is a 240V output too much to use on 110V device when my input is all 110V, using this device as a the on and off indicator.  SSR NEEDED.bmp

                            1 of 1 people found this helpful
                            • 11. Re: Have a question about solid state relays and their applications? Ask me!
                              PeteB

                              Hello Ellis.   The SSR output on this type of temperature controller will typically provide  a DC signal that is used to drive the input of most any "DC input" solid state relay that can accept a 3 to 32 vdc control signal.    I suggest that you first decide on and select a mounting style, (Panel, Din, PCB), listed under the Element 14 product category "Switches & Relays" / "Solid State Relays", and then use the Filters to show narrow down the input voltage range to "3V DC to 32V DC".     Then you can use the additional filters to sort for your load current and operating, (output voltage) ranges.   ( FYI, PCB mount SSR's usually have lower output current ratings than Panel or Din-mount SSR's. )

                               

                              A note regarding your question about 240 Vac output with a 110 vac load.   SSR outputs can handle a wide range.   For instance a 280 vac rated SSR can handle  loads from 24 to 280 vac.     As long as your load voltage is within the range covered by the particular SSR, it will work.  

                               

                              Another note regards your comment about switching an "on and off" indicator.   If you know the current draw of that indicator it would help you to narrow down the SSR maximum switching current rating needed so your load would be handled without using an un-necessarily high current capacity SSR.   Also keep in mind that SSR's have a "Minimum" load current specification.    Your load needs to draw at least that miminum through the SSR output to switch correctly.

                               

                              Pete B.

                              1 of 1 people found this helpful
                              • 12. Re: Have a question about solid state relays and their applications? Ask me!
                                ehagerman2

                                Thanks for the info Pete.  I will check out the Switches and Relays!

                                1 of 1 people found this helpful
                                • 13. Re: Have a question about solid state relays and their applications? Ask me!
                                  pota

                                  Hi Pete, Can you pl help me with this question.

                                   

                                  I am using SSR rated at 3-32 Vdc control and 3A, 240 V load. I connected one terminal of AC supply to load terminal of SSR and other terminal of SSR to common terminal of voltmeter, and another terminal of power supply to the postive terminal of the voltmeter. When I switch on the supply I get 240 even when there is no control voltage applied (It should read 0V as there is no coontrol voltage). When I apply control voltage of 4.5 Vdc, it does not make any difference. Does this mean that  SSR is not working. I purchased four of these, all behaves same. I dont think all are damaged. Am i going wrong somewhere? Please help. I want to make sure that SSR is working before I connect to the circuit. Is it possible that SSR is damaged while soldering to the PCB.

                                  Kind regards, Noone

                                  1 of 1 people found this helpful
                                  • 14. Re: Have a question about solid state relays and their applications? Ask me!
                                    YT2095

                                    Hi Pete,

                                     

                                    a couple of questions for you, How well so SSRs handle inductive loads? the sort that would typically cause arcing with regular relay contacts.

                                    and 2, how well do they handle RF? for instance if I wanted to make an antanna switcher box for Transmitting, would it be able to pass the RF without causing problems to the relay or creating unwanted harmonics.

                                     

                                    Thanks

                                    1 of 1 people found this helpful
                                    • 15. Re: Have a question about solid state relays and their applications? Ask me!
                                      PeteB

                                      Hello Noone.

                                       

                                      Testing a solid state relay is not quite like checking an electro-mechanical relay with a voltmeter.  The solid state relay utilizes a tiny portion of load current to achieve proper operation and the voltmeter does not provide enough of a load to do this.   We have a short "Tech Tip" on the Crydom website (Titled:   How to Test a Solid State Relay),  that describes how to test a solid state relay....   

                                       

                                      http://www.crydom.com/en/Tech/Tips.shtml

                                       

                                      .... and also have a nice "Crydom Tech Lab" video (Episode #1) that covers the subject...

                                       

                                      http://www.crydom.com/en/Tech/TechLab.shtml

                                       

                                      I'm sure this information will help you out.

                                       

                                      Regards,

                                      Pete B.

                                      2 of 2 people found this helpful
                                      • 16. Re: Have a question about solid state relays and their applications? Ask me!
                                        PeteB

                                        Hi "YT".

                                         

                                        SSR's are a great way to switch inductive AC loads, especially for the arcing reason you mention,  as long as the proper "switching type" is used.    For inductive AC loads, the "Random Turn-on" (or "Instantaneous") switching type is recommended, rather than the "Zero-Cross" swithing type.   The "Random" type takes care of the voltage / current phase shift seen with inductive loads which can often cause "Half-Waving" of the output if a zero-crossing SSR is used.

                                         

                                        For most of the Crydom AC output SSR's, the addition of a "-10" suffix to the end of the part number designates a "Random turn-on" relay.  (There are a few types though that utillize an "R" suffix for the random.)   A check of the particular relay datasheet will show the correct part number construction.

                                         

                                        For DC load switching, there is no special designation for switching type on our DC output SSR's.  (They are all "instantaneous" of course.)   For the DC SSR's, it is imperitive to protect the power FET in the SSR output from any inductive "Back EMF" pulse that is produced when the load is switched off.   This is typically achieved with a reverse biased diode applied directly across the load.  This is recommended on ALL DC loads, (not just highly inductive loads), since even a little bit of inductance in the wiring can produce back EMF spikes that exceed the withstanding rating of the DC SSR.

                                         

                                        Regarding RF capability,  the power FET's used for the output switch of DC SSR's do not handle RF. The DC SSR's are not recommended for RF applications.   That need is best suited for "Coaxial Switch relays"  or relays rated for "Microwave" / "RF" use.  They're almost always mechanical contacts.

                                         

                                        Regards,

                                        Pete B.

                                        2 of 2 people found this helpful
                                        • 17. Re: Have a question about solid state relays and their applications? Ask me!
                                          pota

                                          Thank you Pete, that was really useful and it solved my problem.

                                           

                                          Kind regards,

                                           

                                          Noone

                                          1 of 1 people found this helpful
                                          • 18. Re: Have a question about solid state relays and their applications? Ask me!
                                            pulpo

                                            Hi Pete

                                             

                                            I have to admit my knowledge of this subject matter is not good.

                                             

                                            I plan to use a solid state relay controlled by an Arduino.

                                             

                                            I plan to "cut" or stop (not sure of terminology)  the circuit with an SSR

                                             

                                            As most  SSR are normally open (the cheaper ones) I would have to have the SSR permanently in the closed position.

                                             

                                            The SSR would be rated to an output of say 20a 240vac.

                                             

                                            My concern is would it be acceptable to have the SSR always "on" the input current always present 24hrs / 7days 365days?

                                             

                                            The actual load output would be used for say seconds at 15a then back to 4a 240v ac for a total of about 60mins at a time.

                                             

                                            I cannot think of a way to switch the SSR on when its needed, hence just leave the SSR on and break supply when criteria is met.

                                             

                                            Your thoughts are appreciated.

                                             

                                            Many thanks

                                             

                                            Dave

                                            1 of 1 people found this helpful
                                            • 19. Re: Have a question about solid state relays and their applications? Ask me!
                                              PeteB

                                              Hello Dave.

                                               

                                              To your question about having an input signal on 24/7, that is not a problem.  All of our Solid State Relays are designed and rated at "worst case" conditions, and that includes powering the input constantly.

                                               

                                              As for your comment about SSR's and normally open, you are correct in that typically SSR's are only available with NO outputs.   However, Crydom is unique in that we manufacture a normally closed version option within our popular "S1" series.   Take a look at the D2425-BD2425-B, a 3-32 vdc input, 280 vac / 25 amp rated unit.    if you examine the family datasheet for that unit, you'll see that the last item in the part number construction, "Switching Mode", shows that adding a "-B" to the part number provides that normally closed function.

                                               

                                              Regards,

                                              Pete B.

                                              2 of 2 people found this helpful
                                              • 20. Re: Have a question about solid state relays and their applications? Ask me!
                                                pulpo

                                                Many thanks

                                                 

                                                Pete

                                                 

                                                I will have a look at them.

                                                 

                                                D

                                                1 of 1 people found this helpful
                                                • 21. Re: Have a question about solid state relays and their applications? Ask me!
                                                  NKBHATI

                                                  Hi Pete,

                                                  I need a very fast switching (less than 3 micro sec rise/fall time) AC relay/switch  for 520 V (for 415volts phase to phase 50/60 Hz supply with 25% higher voltage ). current rating of 3 Amp normal,but inrush peak current can be 100A for 5 to 10 msec.

                                                  Input control can be from 5 to 12 V DC or upto 24 V .

                                                  please suggest any suitable product from your product range  . also advise me from where I can buy. This is required for a new design of test equipment.

                                                  please advise on  application and surge protection.

                                                  thanks.

                                                  NK BHATI.

                                                  nandkishore.bhati@ymllabs.com

                                                  1 of 1 people found this helpful
                                                  • 22. Re: Have a question about solid state relays and their applications? Ask me!
                                                    PeteB

                                                    Hello NK.

                                                    I'm sorry, but although just about any 10 amp, 530 - 660 Vac rated Solid State Relay can easily handle 100 amp surges fo up to 1/2 AC cycle, the switching speed you require is not possible with SCR / Thyristor based Solid State Relays.

                                                     

                                                    For the turn-on time, since SSR's are relays by definintion, and therefore isolated input to output in some manner, (most are optically isolated), the delay from the time the input signal is applied, passing across the isolation barrier, and then gating the power SCR's,  is greater than what you request.    The typical total turn-on time of a "Random Switching" SSR is on the order of 10 to 20 micro-sec.

                                                     

                                                    As for the turn-off time, with SCR / Thyristor type SSR's that is even a worse situation.  The characteristic of an SCR is that once gated, it will only "turn-off" when the current being passed through it falls to zero,  (actually it needs to fall below its holding current, but it can be considered as zero), which with a resistive load co-incides with the zero-crossing voltage point of the AC half-cycle it was conducting.  Therefore, even with the input signal removed immediately after triggering, the output of the SSR will still be on for the remainder of that half-cycle.

                                                    Regards,

                                                    Pete B.

                                                    1 of 1 people found this helpful
                                                    • 23. Re: Have a question about solid state relays and their applications? Ask me!
                                                      NKBHATI

                                                      Dear Pete, thanks for your prompt response.

                                                       

                                                      I appreciate what you say. However probably  my requirement is not understood well.

                                                       

                                                      The delay is not a  matter of concern. What is required is to verify that with 100 or  1000 ohm termination on output the rise and fall time need  to be less than or equal to  5 microsecond. That means when it starts to turn on or off, it must happen fast. MOSFET relays  for ac application can probably meet this requirement.  Voltage level is 520V (415 V plus 25% range). I am enclosing three pages from IEC 61000-4-11 standard. I am planning to assemble an  equipment for this, but for lower current say 3 A, rather than 16A.  the peak current requirement will also be accordingly lower , say 100A. the test method is suggested in this standard. The switch or relay will be used for Switch 1 and 2 as given on last page.

                                                       

                                                       

                                                       

                                                      Is there any suitable product in CRYDOM  product range. Or can you suggest suitable parts for discrete implementation.

                                                       

                                                      Please suggest me some suitable application notes/ reading material for this.

                                                       

                                                      Thanks.

                                                       

                                                      NK BHATI.

                                                      1 of 1 people found this helpful
                                                      • 24. Re: Have a question about solid state relays and their applications? Ask me!
                                                        PeteB

                                                        NK.

                                                         

                                                        Thank you for sending the standard information, very interesting.   As for the actual switching transisiton time, I am sorry, but our switching times do not come close to your requirement of 5usec or less.    According to our Engineering group, the on transisiton time we include in the total turn-on time for our fastest DC output SSR's is 50 usec, while the off transisiton time is 70 usec.

                                                         

                                                        I do not have any additional suggestions available for discrete circuitry, nor related application information.

                                                         

                                                        Regards,

                                                        Pete B.

                                                        1 of 1 people found this helpful
                                                        • 25. Re: Have a question about solid state relays and their applications? Ask me!
                                                          NKBHATI

                                                          Dear PeteB, thanks for your mail.

                                                           

                                                          I am grateful for your response.

                                                           

                                                          If not now, it will be useful in future for other work.

                                                           

                                                          Thanks.

                                                           

                                                          NK BHATI.

                                                          1 of 1 people found this helpful
                                                          • 26. Re: Have a question about solid state relays and their applications? Ask me!
                                                            fitimismaili

                                                            hi there,

                                                             

                                                            my question may look like stupid question but i dont understand much of the electronics (im a programmer). Lastly i faced a problem with a device in my house. I need to change a HKE HRS4H-S-DC12V. The problem I have is that I cant find to buy the same model of this relay on ebay.com to replace with. so  i didnt wanted to make a mistake and burn things out . Can you please tell me what can be the perfect match with this relay on ebay.

                                                             

                                                            Thank you in advance

                                                             

                                                            Please help me.

                                                             

                                                            sincerealy,

                                                            1 of 1 people found this helpful
                                                            • 27. Re: Have a question about solid state relays and their applications? Ask me!
                                                              PeteB

                                                              Hi. 

                                                              I'm sorry, but I can't be of much help to you regarding looking for an HKE relay or what could be the perfect match for it.     This is an electromagnetic / mechanical relay to begin with, and Crydom manufactures only Solid State Relays.   Replacing an electromagnetic relay with a solid state relay is not a trivial task, (many circuit characteristics need to be taken into consideration), and I'm sure that is not what you intend.  I would suggest you work with a friend or contact who is technically competent, to obtain the specifications for the HKE relay you have, and then select a mechanical relay that would be of similar characteristics for your replacement.

                                                              - Pete B.

                                                              1 of 1 people found this helpful
                                                              • 28. Re: Have a question about solid state relays and their applications? Ask me!
                                                                khbilen

                                                                Hi Pete,

                                                                 

                                                                Can you help me on testing SSRC 04 type Level Control Relays? How do I read the output voltage, or lght an AC bulb as the output?

                                                                 

                                                                Thanks,

                                                                 

                                                                Kadir

                                                                1 of 1 people found this helpful
                                                                • 29. Re: Have a question about solid state relays and their applications? Ask me!
                                                                  PeteB

                                                                  Hello Kadir.

                                                                   

                                                                  The SSRC 04 Type level control relay is not a Crydom product, but it does appear to utilize an SPDT mechanical relay as the output.   As such, you should be able to test the output switching simply by measuring continuity and wathcing for a change-over from the normally closed contact to the normally open contact.

                                                                   

                                                                  For more detailed information I suggest you contact the manufacturer of that device.

                                                                   

                                                                  Pete B.

                                                                  1 of 1 people found this helpful
                                                                  • 30. Re: Have a question about solid state relays and their applications? Ask me!
                                                                    khbilen

                                                                    Thanks Pete,

                                                                     

                                                                    That is exactly my problem. When the tank is full, the RED LED is on, indicating there is some output somewhere (as you say, 1-2 is NC, and 1-4 is NO), but I can not see any voltages anywhere: 1-2, 1-4, 2-4. So, does this mean the switch is definitely malfunctioning, or am I looking at wrong terminals. There is nothing at A1-1, A1-2, A1-4, A2-1, A2-2, A2-4 either while there are some voltages at U-L, U-B, L-B, and of course A1-A2; so the inputs are there, I can not see any output.

                                                                     

                                                                    Can I normally connect the AC light bulb to 1-4 directly (with no serial resistors or anything like that), without blowing up the bulb?

                                                                     

                                                                     

                                                                    Kadir

                                                                    1 of 1 people found this helpful
                                                                    • 31. Re: Have a question about solid state relays and their applications? Ask me!
                                                                      khbilen

                                                                      Hello Pete,

                                                                       

                                                                      I have found the problem. I had made an incorrect assumption, that the output terminals were internally powered bu the switch itself. That was not true. You have to provide the power to the switching terminals, so that you get the desired voltage at desired state. So, the output of the relay switch itself is not a power, but just a powerless state.

                                                                       

                                                                      Thanks.

                                                                       

                                                                       

                                                                      Kadir

                                                                      1 of 1 people found this helpful
                                                                      • 32. Re: Have a question about solid state relays and their applications? Ask me!
                                                                        trelevn

                                                                        Dear Pete,

                                                                         

                                                                        A project I thought was simple is proving difficult. I want to remotely power on an audio amplifier powered by a 240 Volt 160VA torodial transformer. A first attempt was to put a 3 Amp solid state relay in parallel with the on/off switch on the transformer primary. But when it should be off the SSR: leaks, half waves, or has sufficient capacitance, to leave 20 Volts AC on the transformer primary, half-powering it. The power supply LEDs come on with 5 of the 50 Volts they produce when switched on. Not a good way to leave it when it should be off. I don't want to use an electro-mechanical relay for noise and EM field reasons.

                                                                         

                                                                        Any suggestions?

                                                                        2 of 2 people found this helpful
                                                                        • 33. Re: Have a question about solid state relays and their applications? Ask me!
                                                                          PeteB

                                                                          Hi Michael.

                                                                           

                                                                          You don't note the particular model of Solid State Relay you're using so I can't confirm this, but what you're most likely experiencing is the result of the "off-state leakage current" value of that SSR.     It most likely has an internal "R-C" (resistor / capacitor) snubber network commonly placed across the output to improve commutating characteristics, and those typically can allow up to 10ma at 240 vac to flow through the output in the off-state.  In a lot of applications, a snubber equipped SSR is not necessary, and as you've likely seen, it can created an unexpected condition.

                                                                           

                                                                          Look for an SSR that is "snubberless"  or look for an "off-state leakage current" spcification value of less than 1ma.  That typically means the relay is snubberless.

                                                                           

                                                                          Pete B.

                                                                          1 of 1 people found this helpful
                                                                          • 34. Re: Have a question about solid state relays and their applications? Ask me!
                                                                            trelevn

                                                                            Thanks for that Pete. Yes the leakage current on my SSR is 5mA. I'll look around for a better model, any suggestions?

                                                                            1 of 1 people found this helpful
                                                                            • 35. Re: Have a question about solid state relays and their applications? Ask me!
                                                                              000Plasma000

                                                                              A quick question (okay, two if you look closely...) -

                                                                               

                                                                              What's the advantage of a relay over, say, a MOSFET transistor? Transistors can handle much faster switching speeds I belive. Is it just to do with AC current?

                                                                               

                                                                              Thanks in advance

                                                                              1 of 1 people found this helpful
                                                                              • 36. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                PeteB

                                                                                What part number SSR are you using presently?   That info would help so I can suggest a similar package style without a snubber.

                                                                                1 of 1 people found this helpful
                                                                                • 37. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                  PeteB

                                                                                  Hi Rahul.    I'd even accept 3 questions if you like. 

                                                                                   

                                                                                  You ask what is the advantage of using a solid-state relay vs. using a discrete device like a MOSFET ?    A solid state relay provides a means of completely isolating the power switching element, (which in the case of DC output solid state relays is most often a power MOSFET), allowing the use of completely different signals for input and output, along with no need to be concerned with "low" or "high" side drivers to control the discrete FET.

                                                                                   

                                                                                  You also mention AC current along with asking about Transistors so I would like to explain a bit about the power elements used in solid state relays.   Typically, for power SSR's,  the type is specific for AC vs. DC switching.      AC loads are switched with dual inverse parallel SCR's, while SSR's suitable for switching power DC loads utilize either Bi-polar transistors, or MOSFET's.  

                                                                                   

                                                                                  As for switching speed, an SSR can't match the switching speed of a discrete device since there is a bit of a finite "propogation delay" from the input side across the isolation barrier, to the driving of the power device, but we produce MOSFET based DC SSR's that will switch in less than  75-100 usec.   As for AC output SSR's using the dual SCR's mentioned, the random turn-on (instantaneous switching), typically will switch within 20 usec.

                                                                                   

                                                                                  Does this answer your questions?   Or did I mis-understand the intent of your questions?

                                                                                  • 38. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                    trelevn

                                                                                    Dear Pete,

                                                                                     

                                                                                    This is the part I grabbed at the local Jaycar store:

                                                                                      http://www.jaycar.com.au/products_uploaded/SY-4080.pdf

                                                                                     

                                                                                    This form is fine for my case but it doesn't really matter, I'm just soldering wires, heatshrinking them to protect them and tucking it away.

                                                                                     

                                                                                    Easy to get is more important, an element14 supplied part would be good.

                                                                                     

                                                                                    Thanks again, you're a real help,

                                                                                    michaelj

                                                                                    • 39. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                      PeteB

                                                                                      Hello Michael.

                                                                                       

                                                                                      If you are satisfied with the form of your present SSR, then my Crydom part suggestion would be either the CX (powder epoxy coated) or the MCX (plastic encased) series of SSR's.   One note to make would be that with these (snubberless) series, the input voltage range is split between 4-15 Vdc and 15 - 32 vdc, rather than a wide input range of 4 - 32 vdc.    Specifically for 4 to 15 Vdc control the pn's would be CX240D5 or MCX240D5RMCX240D5R, and for 15 to 32 Vdc control, the pn's would be CXE240D5CXE240D5 or  MCXE240D5MCXE240D5 The output rating on all of these part nubmers are the same can handle up to 5 amp at 280 vac

                                                                                      Here are the links to the CX and the MCX datasheets....

                                                                                       

                                                                                      http://www.crydom.com/en/Products/Catalog/c_x.pdf

                                                                                      .

                                                                                      http://www.crydom.com/en/Products/Catalog/m_c_x.pdf

                                                                                       

                                                                                      My quick check through the Farnell Element 14 Stores shows plenty of stock on hand worldwide.

                                                                                       

                                                                                      Regards,

                                                                                      Pete B.

                                                                                      • 40. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                        trelevn

                                                                                        Dear Pete,

                                                                                         

                                                                                        Your help has resolved my problem.

                                                                                        Once you gave me the right part number it was easy to order through element14.

                                                                                        They had them to my door in less than 2 days.

                                                                                         

                                                                                        The solid state switch you recommended reduces the off state voltage

                                                                                        seen by the transformer primary from 20 Volts to 50 mV.

                                                                                         

                                                                                        Thanks so much for your help,

                                                                                        I was trying to use element14's part searching filters

                                                                                        but just didn't have the knowledge to come up with the right part.

                                                                                         

                                                                                        michaelj

                                                                                        • 41. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                          PeteB

                                                                                          Glad to have helped, Michael.  Thanks for letting us know it's now working as you expected.

                                                                                          Pete B.

                                                                                          • 42. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                            tow2topgun

                                                                                            I'm using an Omega CN742 temp controller (DIN) to control a 110v heating element along with a RTD. I was told that i would have to power the heating element with a SSR. Well, i have the 110v power hooked into the din and then the ssr is wired separate of the ac. I havepower to the ssr and the led is illuminated. However i have no output power from the ssr to the heating element.

                                                                                            Any ideas?

                                                                                            • 43. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                              tow2topgun

                                                                                              I'm using an Omega CN742 temp controller (DIN) to control a 110v heating element along with a RTD. I was told that i would have to power the heating element with a SSR. Well, i have the 110v power hooked into the din and then the ssr is wired separate of the ac. I havepower to the ssr and the led is illuminated. However i have no output power from the ssr to the heating element.

                                                                                              Any ideas?

                                                                                              • 44. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                tow2topgun

                                                                                                I'm using an Omega CN742 temp controller (DIN) to control a 110v heating element along with a RTD. I was told that i would have to power the heating element with a SSR. Well, i have the 110v power hooked into the din and then the ssr is wired separate of the ac. I havepower to the ssr and the led is illuminated. However i have no output power from the ssr to the heating element.

                                                                                                Any ideas?

                                                                                                • 45. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                  tow2topgun

                                                                                                  I'm using an Omega CN742 temp controller (DIN) to control a 110v heating element along with a RTD. I was told that i would have to power the heating element with a SSR. Well, i have the 110v power hooked into the din and then the ssr is wired separate of the ac. I havepower to the ssr and the led is illuminated. However i have no output power from the ssr to the heating element.

                                                                                                  Any ideas?

                                                                                                  • 46. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                    PeteB

                                                                                                    Hi Jason. 

                                                                                                     

                                                                                                    Indeed, the use of the CN742 to drive a Solid State Relay will provide you with a very accurate and even temp control, since the "Pulsed DC output" of that control is intended to be used with SSR's  which can react to extremely short pulses, and operate at cycle rates well beyond what a mechanical relay can handle.

                                                                                                     

                                                                                                    From your description of how you've wired the heater to the SSR, I believe you might be under a slight misunderstanding of what a Solid State Relay is.  It will not convert the low voltage DC pulse output from the controller to the AC line power required by your heater.    The output of the SSR is easiest envisioned as simply a power switch.     The connection scheme is to wire one side of the line power through the SSR output "switch", ( the "switch" essentially is between the two terminals labeled as "Output" ),  then to one side of your heater load, and then from the other side of the heater back to the other side of the AC line.   When the temp controller applies the signal to the SSR input, (sounds like you have that correct as the input LED indicator comes on), the SSR "switch" will close and operate your heater.

                                                                                                     

                                                                                                    We've got a Crydom "Tech Lab" video on our website that will show you the typical wiring of the SSR with an AC load.   This video covers the bench testing of an SSR, but it clearly shows how the output of a basic SSR is wired.   Here's the link to our Tech Lab Videos, and Episode 1 is the video I'm referencing here.

                                                                                                     

                                                                                                    http://www.crydom.com/en/Tech/TechLab.shtml

                                                                                                     

                                                                                                    I'm sure this will help your understanding. 

                                                                                                    Pete B.

                                                                                                    • 47. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                      tow2topgun

                                                                                                      Pete, thank you do very much. The video and your advice have set me straight. You were correct in thinking that i was misunderstanding.Again, thank you very much. I'll wire it up as soon as i get home from work today.

                                                                                                      • 48. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                        PeteB

                                                                                                        You're welcome, Jason.    Glad to help.

                                                                                                        Pete B.

                                                                                                        • 49. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                          tow2topgun

                                                                                                          So the problems continue.....I got it all wired up and it was working great. The PID was set for the temp to be 173F and the liquid to be heated was around 58F. I let it run for about 30 mins and started to notice a burning odor. I picked up the PID and SSR to smell of it to see if the odor was cominng from one of them. I then heard a crackling sound coming from the SSR. I unplugged the unit and shortly thereafter, the metal back plate on the SSR fell off.

                                                                                                          My SSR is a SSR330DC10 from Omega and the PID is a CN742 also from Omega. Any ideas as to why it would have reached such high temps so rapidly? Should I maybe be using a larger SSR?

                                                                                                          • 50. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                            PeteB

                                                                                                            Jaso

                                                                                                             

                                                                                                            This sounds to me as a failure due to inadequate / improper heatsinking.   Provided in the information for most SSR's, there is a thermal derating / heatsinking chart that notes what the proper heatsinking should be for the particular load current in the application, along with the maximum expected ambient temperature that will be surrounding the heatsink / SSR assembly.   All AC output SSR's produce approximately 1 to 1.5 watts of internal heating PER Load Amp, due to the semiconductor voltage drop.   So for instance, a 5 amp load would produce 5 to 7.5 watts of internal heat that must be removed by proper mounting of the SSR onto a properly sized heatsink. 

                                                                                                             

                                                                                                            I can't speak specifically for Omega SSR's, but proper operation for 30 minutes and then the baseplate falling off  with buring smell is a definite indication of the inside of the SSR getting too hot.

                                                                                                             

                                                                                                            Episode #2 and #3 of our tech lab videos explains this well.   

                                                                                                             

                                                                                                            http://www.crydom.com/en/Tech/TechLab.shtml

                                                                                                             

                                                                                                            Pete B.

                                                                                                            • 51. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                              group7

                                                                                                              Mr. Bamburak,


                                                                                                              Is it true that SSRs outputs must have a minimum load current? What happens when the SSR needs to work more like a regular switch than for example, a load current limiter?

                                                                                                              While considering a SPST-NO SSR, I had thought that when the control voltage is applied to the input of the relay, the SSR would be basically closing a switch on the Output poles just like Electromechanical relays do, thus allowing continuity (less than 1 Ohm) between the output poles, regardless of a working load and load current.

                                                                                                               

                                                                                                              Maybe related, here's another headache... When reading "Output Voltage Range: 3–150 Vdc" on the Specs sheet, how come you can't have a 0-150Vdc range?

                                                                                                               

                                                                                                              I appreciate your comments to resolve this confusion.

                                                                                                               

                                                                                                               

                                                                                                              Regards,

                                                                                                               

                                                                                                              Andres G.

                                                                                                              • 52. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                PeteB

                                                                                                                Hi Andres.

                                                                                                                 

                                                                                                                Regarding minimum load current requirements, for SSR's that switch AC loads using power SCR's or Triac's, yes that is indeed true.  Those devices that comprise the output "switch" of the SSR require gating current to trigger at the beginning of every AC half-cycle.   That initial gating current must flow through the load and if it is not sufficient the SSR will not operate.    Depending on the size of the power SCR's, the minimum load current requirement can range from 25ma to 150ma.

                                                                                                                 

                                                                                                                Minimum load requirements for DC output SSR's utilizing power MOSFET's are a different story.  Since the gating of FET's is through voltage rather than current driven, that gating voltage can be supplied relatively easily across the isolation barrier, (from input to the output), typically done via a photo-voltaic or transformer coupling method.   Therefore gating power is not needed through the load.   Our specified minimum loads for our FET based DC output SSR's range from 1ma to about 5ma.   Why they are not shown as 0ma is due to the fact that the internal output circuitry that speeds up the turn-on and turn-off of the power FET needs a very slight bit of load current flow to be effective.   Therefore we post that minimum load current to be sure that the specified operating times are met.

                                                                                                                 

                                                                                                                As for "continuity" between the output terminals, this again differs between the AC output and DC output SSR's.   The AC output SCR's produce a relatively constant voltage drop, (Vf),  same as other bi-polar devices such as diodes over the load current range, and will as described above, require load current to switch on. Placing an ohmmeter across the output terminals does not provide a sufficient load to operate the SSR.      DC SSR's using power MOSFET's show a resistance characteristic (Rds-on) that produces a varying voltage drop depending on the load current. This is an inherent characteristic of the FET's.   The typical Rds-on ranges for our FET based DC output SSR's ranges from 0.8 ohm down to 0.005 ohm depending on the SSR model.

                                                                                                                 

                                                                                                                Regards,

                                                                                                                Pete B.

                                                                                                                • 53. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                  relayinfoneeded

                                                                                                                  Where can I get a SSR that will handle 30A DC non inductive load at 250Volts working and 2000V isolation?

                                                                                                                  Contol input = 5V prefered.

                                                                                                                  • 54. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                    PeteB

                                                                                                                    Hello John.

                                                                                                                     

                                                                                                                    Unfortunately with DC output SSR's as working voltages go up the current ratings tend to go down Your particular combination of 250 Vdc and 30 amp load is just beyond the range of our  DC400D20DC400D20 model which can handle 300 Vdc and 20 amp We have higher DC voltage rated SSR's(up to 1000 Vdc and current ratings up to 160 amp but not at all combinations of voltage and current

                                                                                                                     

                                                                                                                    Fortunately DC SSR's using power MOSFET technology are easily paralleled to increase the load current rating In this instance 2 of the  can be paralleled to have a rating of 40 amp at 300 working volts The  DC400D20DC400D20 control input of 4 to 32 vdc and the isolation rating of 2500 V cover your remaining specifications

                                                                                                                     

                                                                                                                    The Element 14 store has sotck on hand of both the  DC400D20DC400D20 and the DC400D20C(the"C designates an included IP20 clear cover

                                                                                                                     

                                                                                                                    Regards,

                                                                                                                    Pete B.

                                                                                                                    • 55. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                      Injunear

                                                                                                                      Hello,

                                                                                                                       

                                                                                                                      I am looking for a simple way to use the outputs of a 3V3 microcontroller (KL25Z-FRDM board) to control (1) several 24V 1.5A hydraulic valves , (2) a few 100-240 VAC solid state relays, (3) a single pole double throw 120 VAC relay, and (4) a double pole double throw 120 VAC relay.

                                                                                                                       

                                                                                                                      I have working circuits for each of these functions but I would like to use fewer components to accomplish these tasks. I am hoping that Crydom (or some other vendor) will have, ideally, a single component that will replace the multiple components I am currently using for each individual output.

                                                                                                                       

                                                                                                                       

                                                                                                                      What I desire:

                                                                                                                      All device inputs activated by ~ 3VDC (or less) at 2mA or preferably less,

                                                                                                                      1 – a device that will switch 24 VDC at >= 1.5A

                                                                                                                      2 – a device that will switch 100-240 VAC at <= 25A

                                                                                                                      3* – a device that will act as a single pole double throw relay for 120 VAC at ~10A

                                                                                                                      4* – a device that will act as a double pole double throw relay for 120 VAC at >=12A

                                                                                                                      * - If these devices are not available, then a device that will act as a 5 VDC solid state relay @ >= 500mA will at least replace two components.

                                                                                                                       

                                                                                                                       

                                                                                                                      For example, in order to activate either of the double throw relays (item numbers 3 & 4), I have two 3V3 GPIO outputs of the MCU go into a SI8660 chip (Silicon Labs 6 ch digital voltage isolator) which translates the signal to 5V.  The signals then go into two PS710B-1A chips and their outputs drive the coils of PCB mounted mechanical relays.

                                                                                                                      Is there any device that will take the MCU output (<= 3VDC at 2mA or less) and activate a 120 VAC double throw relay (single or double pole)? Failing that, is there a device that will take the MCU output and provide a switched 5VDC output > 0.5 A? This would at least replace the SI8660 and PS710 I am currently using for each control signal.

                                                                                                                       

                                                                                                                      For the other outputs I have successfully used the SI8660 chip to drive a 100-240 VAC 25 A Solid State Relay (item number 2), and an IPS7091 (International Rectifier “Intelligent Power Switch”) (item number 1). (I included pull down resistors on the output of the SI8660 to make sure the signal did not float.) That configuration has seemed to work reliably for several months of testing.

                                                                                                                       

                                                                                                                      [I am currently experimenting with the TI TXB0108 chip (TI 8 channel bi-directional voltage level isolator) to drive both the SSRs and the IPS7091s. I am hoping to do away with the pull down resistors and also have eight channels of bi-directional I/O, but I am not sure if this is an appropriate application for this chip.]

                                                                                                                       

                                                                                                                      However, my preference would be to use a device that will use the MCU output directly to switch 24VDC @ >=2A, and another device that will use the MCU output to drive an SSR which switches 100-240VAC @ 25A.

                                                                                                                       

                                                                                                                      My question is simply, do you know of any devices that will use the MCU outputs I have to perform any of the functions listed in numbers 1-4?

                                                                                                                       

                                                                                                                      Thank you.

                                                                                                                      • 56. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                        PeteB

                                                                                                                        Hi Injun.

                                                                                                                         

                                                                                                                        To answer your simple question at the end of your note, I'm sorry, but we have no SSR's in our product line that would meet your SSR input requirement of 3 Vdc and 2ma or less.  

                                                                                                                         

                                                                                                                        Now, if you were able to use your mico's outputs to each drive a small transistor as a negative logic interface to sink at least 4 -5 ma from a separate DC source providing at least 3 Vdc across the SSR's input, our S1 Series, (i.e.  the D2410 , D2425 ), only requires about 3.4 ma as an input to operate and would easily cover your #2 requirement.    This AC output switching series has the lowest input current requirement of any SSR we manufacture.    Addtionally, with the availability of the "-B" option, (normally closed version), using multiple normally open and normally closed units you could configure SPDT and DPDT systems for your #3 and #4 needs.   You would of course need to take precautions that you've got sufficient delays in switching between the NO and NC poles if you've got a system that needs a complete "off" point between transisitons.   Unfortunately, we do not manufacture a combined, single package, "Form C" (SPDT), SSR.

                                                                                                                         

                                                                                                                        As for the DC load switching requirement of #1, (24Vdc at 1.5 amp), we are a little closer to your 3 vdc / 2ma but still not completely met, with our Bipolar Power Transsitor output based, DC60S3 unit.   This unit needs at least 3.5 Vdc, but at that voltage will draw slightly less than 2ma.  ( FYI, the DC60S series is unique in the industry since it is also available with the "-B" normally closed option. )

                                                                                                                         

                                                                                                                        I hope this is helpful, but again, unfortunately no ideal match to your requirements.

                                                                                                                         

                                                                                                                        Pete B.

                                                                                                                        • 57. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                          Injunear

                                                                                                                          Thank you very much for the help.

                                                                                                                           

                                                                                                                          I will consider your suggestions and see how they compare with whatever else I might come up with.

                                                                                                                           

                                                                                                                          Thank you again.

                                                                                                                          • 58. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                            tefa627

                                                                                                                            Hey Pete,

                                                                                                                             

                                                                                                                            I have an AC SSR relay with an indicating LED. I am hoping to use the relay to turn on and off an air conditioner. For right now, I am creating a prototype that will just turn on and off an LED. The built in LED works when connected to my arduino. But my load(LED) does turn on and off. I think this is because I am using DC voltage to power my LED. What would you recommend me doing? Is there anyway i can switch my LED on and off with DC voltage? Or do I need a different relay? Thanks.

                                                                                                                            • 59. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                              PeteB

                                                                                                                              Hi Temi,

                                                                                                                               

                                                                                                                              You've got two issues here.  First, AC output SSR's are only designed to switch AC loads.   The second issue is that even if you were using a very small AC lamp as an indicator, you'll need to meet the "minimum load current" spec requirement.  That is typicall 50 to 100 ma depending on the model of SSR.

                                                                                                                               

                                                                                                                              Your objective to operate an air conditioner is perfectly suited for an SSR, (be sure to use a "Random turn-on" version since the load will be considered inductive), and be sure to consider the heatsinking needs adequately.

                                                                                                                               

                                                                                                                              As for testing your control and the interface to the SSR for operation, simply use a 60 or 100 Watt lamp as a testload.that the output of the SSR is operating. 
                                                                                                                              You can refer to the Crydom Website for the short note on "Testing an SSR".....

                                                                                                                               

                                                                                                                              Link:     http://www.crydom.com/en/Tech/Tips/How%20to%20test%20an%20AC%20solid%20state%20relay.pdf

                                                                                                                               

                                                                                                                              Or check out our video on the same topic.....  http://www.youtube.com/embed/bzrsE4tTJP8

                                                                                                                               

                                                                                                                              I'm sure those will help you out.

                                                                                                                               

                                                                                                                              Regards,

                                                                                                                              Pete B.

                                                                                                                              • 60. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                tefa627

                                                                                                                                Thank you, I will definitely use a small lamp for my second prototype, but for right now I want my first prototype to be a simple model, switching on and off an LED. This is my first time using relays and I want to take baby steps. Since an LED does not meet the "minimum load current" spec requirement, I will change the relay to a DC SSR. Do you think that would work? Or do you have any other suggestions? Thanks again!

                                                                                                                                • 61. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                  PeteB

                                                                                                                                  You can certainly use a DC output SSR for your experimentation if you like.     Our DC60S3 is a cost effective "Bi-polar Transistor" output type DC SSR, and only requries a 20ma minimum load.  If your single LED load does not pull that much, you could always increase it by paralleleing additional LED's.    Here's the link to that DC60 series datasheet....

                                                                                                                                   

                                                                                                                                  http://www.crydom.com/en/Products/Catalog/d_c60.pdf

                                                                                                                                   

                                                                                                                                  Our MOSFET output type SSR's can typically switch extremely low currrent loads if you'd like to try that type The D1D07 would be a good panel mount one to use even though it can handle up to 7 Adc If you'd like to try a smaller relay our  DMO063DMO063 pcb type SSR(up to 3 Adc max would do fine to switch the LED

                                                                                                                                   

                                                                                                                                  http://www.crydom.com/en/Products/Catalog/dm_o.pdf

                                                                                                                                   

                                                                                                                                  For the DC SSR's, be very careful to follow the wiring polarities.   Unlike the AC output SSR's, you could possibly damage the DC output SSR's by incorrectly wiring your load circuits.   The load wiring is shown on each of the datasheets.    For the exact SSR model number selection, be sure to choose the correct input voltage range for your controller, along with ensuring that the output voltage range of the SSR covers your requirements.

                                                                                                                                  • 62. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                    gravydave

                                                                                                                                    Hi Pete

                                                                                                                                    I used a SSR to remotely control the dust collector in my wood shop.  The first one froze in the on position and I am worried about hooking my new one up.  I just don't want to have to buy another.  Anyway the first one was not a random turn on SSR Aand worked fine when hooked to a lamp.  Could this have caused it to lock up?  So my new SSR is a crydom D4825-10 and it will control a 110v 20A 2hp motor. Is there some protection I should add to the relay and how would I wire it?  Or is this relay too small for the motor I want to run? The first relay was eight dollars new rated at 20 A. 

                                                                                                                                     

                                                                                                                                    Thanks for your help

                                                                                                                                    Dave

                                                                                                                                    • 63. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                      PeteB

                                                                                                                                      Hi Dave.

                                                                                                                                       

                                                                                                                                      The use of a random turn-on SSR (the Crydom "-10" suffix as you've done on the D4825), for motor loads is always recommended and you're on the right track.   Checking out the SSR operation with a lamp is a very good way to see that at least the operation and your wiring is correct.

                                                                                                                                       

                                                                                                                                      Regarding the failure you experienced wth your eight dollar 20amp relay, that unit was likely a triac based power output.   Triac output SSR's are usually less costly, but very prone to problems wth any load other than simple lamps, resistive heaters, etc.   Just about all of Crydom's AC output SSR's utilize dual inverse parallel power SCR's for the output "switch".   Using 2 separate semiconductor devices produces a much more robust SSR for motor loads.  (The D4825-10 you note is indeed a dual SCR unit).

                                                                                                                                       

                                                                                                                                      Now to the particular relay i wuld recommend:   If your motor is truly a 2 hp / 110 vac unit, our SSR selector tool for motor loads...

                                                                                                                                       

                                                                                                                                      http://www.crydom.com/en/Tools/Selector_Motor.shtml

                                                                                                                                       

                                                                                                                                       

                                                                                                                                      ...shows that the FLA for that type of motor is typically 24 amp, and the recommended SSR (which would include UL recognized HP ratings), would be a 50 amp model.   Speifically, either the CWD2450-10 (24 to 280 vac output), or the CWD4850-10 (48 - 660 vac) would be well suited for your motor.    Regarding the D4825-10, it's 25 amp max rating would be a bit too close to that 24 FLA load, (but if your motor is truly 20 amp, should be sufficient with proper heatsinking...more to come about that...).  The reason I mention the CW series is that with that series, Crydom started specifically adding the UL Recognized HP ratings to make it easier for those OEM's needing to relate theSSR to the UL ratings for their system UL Listings.

                                                                                                                                       

                                                                                                                                      Finally, don't forget that the use of an adequate heatsink is essential to the reliability and long life of the SSR in your appication.   The SSR datasheet will have derating curves that help select the correct heatsink.  Additionally, we hav another website tool, the Heatsink / Heatsink selector tool. 

                                                                                                                                       

                                                                                                                                      http://www.crydom.com/en/HSseries/hs_assy_selector.shtml

                                                                                                                                       

                                                                                                                                      Just click first on "Heat Sink" in the upper right and then you can enter the various parameters and conditions that will then result in a selection of accessory heatsinks.

                                                                                                                                       

                                                                                                                                      Good luck with your dust collection system !

                                                                                                                                       

                                                                                                                                      Pete B.

                                                                                                                                      • 64. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                        gravydave

                                                                                                                                        Thank you so much for your help.  I will definitely look into heat sink and make sure mine is of correct size.  Thanks again and hopefully it will work out well.  From what I understand about my dust collector its over rated.  So its possible it won't pull 20 A of current.  I guess harbor freight makes things looked better on paper than they really are.  Thanks again

                                                                                                                                        • 65. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                          daveabraham

                                                                                                                                          Hi Pete,

                                                                                                                                           

                                                                                                                                          I am using a Magnecraft W6410ASX-1 SSR in a circuit where the SSR output is in series with a  240  vac transformer secondary coil and a motor contactor coil. Sometimes  the ac supply to the SSR output is 0 volts, because the transformer  primary input is turned off, while the SSR input is 120 vac . It has  been operating this way for a few days without any problems.

                                                                                                                                           

                                                                                                                                          Will this cause the SSR to fail eventually ?

                                                                                                                                           

                                                                                                                                          If so, can you explain why or point me to a information source on the internet that covers this topic ?

                                                                                                                                           

                                                                                                                                          Thanks,

                                                                                                                                          Dave

                                                                                                                                          • 66. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                            PeteB

                                                                                                                                            Hi Dave.  

                                                                                                                                            Having power applied, (of couse wihin specification limits), to the input of an SSR while there is no load voltage present on the output side has absolutely no detrimental effect on SSR.   Since most Solid State relays are optically coupled, the only thing that is crossing the isolation gap / barrier from the input side to the output side is light.   With no output voltage applied, the light sensitive output side half of the opto coupler just simply won't react to that light.

                                                                                                                                             

                                                                                                                                            Hope this eases your concerns !

                                                                                                                                            Pete B.

                                                                                                                                            • 67. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                              diagabordo

                                                                                                                                              Hi Pete!

                                                                                                                                               

                                                                                                                                              I have a question for you.

                                                                                                                                               

                                                                                                                                              First of all, I read all the post and thank you in advance for your help.

                                                                                                                                               

                                                                                                                                              I tell him what happens to me.

                                                                                                                                               

                                                                                                                                              Using an Opto-MOSFET SSR (TLP3215 - Toshiba) I've put a test to see if it really works well.

                                                                                                                                               

                                                                                                                                              The problem I've found in this type of SSR is that when I put a square sign at the entrance 5Vpp SSR, this when you have to cut the power to be at rest, output is reflected in the 10% of the input signal.

                                                                                                                                               

                                                                                                                                              When this mode turned ON, it works correctly at different frequencies.

                                                                                                                                               

                                                                                                                                              The only way you can not see residual signal is output DC voltage.

                                                                                                                                               

                                                                                                                                              Is there any way to eliminate this excess voltage?

                                                                                                                                               

                                                                                                                                              I think it is due to internal leakage of SSR.

                                                                                                                                               

                                                                                                                                              Thanks again, and received a cordial greeting.

                                                                                                                                              • 68. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                PeteB

                                                                                                                                                Hello Antonio.

                                                                                                                                                 

                                                                                                                                                I am very sorry, but I am not familiar with the characteristics of the TLP3215.  I would suggest that you contact Toshiba for support on this.

                                                                                                                                                 

                                                                                                                                                Regards,

                                                                                                                                                Pete B.

                                                                                                                                                • 69. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                  diagabordo

                                                                                                                                                  Hi Pete!

                                                                                                                                                   

                                                                                                                                                  Thanks for you fast reply.

                                                                                                                                                   

                                                                                                                                                  Today'll contact toshiba Spain. Let's see if they can help me. Thank you.

                                                                                                                                                   

                                                                                                                                                  Best Regards!

                                                                                                                                                  • 70. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                    tommead

                                                                                                                                                    I've looked at a couple of EMC test waveforms showing the conducted noise produced by solid state relays including Crydom. They all show emissions which exceed the EN500081-1 noise limit even when using a Crydom EMC filter.  Adding a noise filter to the circuit is very expensive and negates the advantage over EM relays.

                                                                                                                                                    • 71. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                      pauldse

                                                                                                                                                      Hi Pete,

                                                                                                                                                       

                                                                                                                                                      I'm hoping to design a SSR circuit to switch quickly between a mains-driven 500W 12v supply (utilising an ATX PSU) and a couple of big 12V deep-cycle batteries in parallel to create a sort of UPS but with the option of running off battery when in the field and hopefully being v quiet (for use on a film set).  The output will power an array of hard-drives and a laptop, plus a second monitor.  Could you tell me if I am on the right track with the accompanying schematic, please, as well as how I might work out the values for the T1 R1,2,3 and C1.  Also if I have spec'ed the SSR correctly.  Many thanks for any help!

                                                                                                                                                       

                                                                                                                                                      All best,

                                                                                                                                                       

                                                                                                                                                      Paul

                                                                                                                                                       

                                                                                                                                                      50A psu battery switching SSR simpler.png

                                                                                                                                                      • 72. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                        PeteB

                                                                                                                                                        Hello Tom.   I apologze for not replying to you sooner, but it appeared my notificaiton of a question has not been operational for a month or so.   Regarding your comment, it is indeed true that the switching characteristics of power SCR's produce a level of conducted noise.  This is due to the fact that the AC voltage must rise high enough across the SSR output at the beginning of every AC half-cycle to porduce sufficient gating current for the SCR to trigger, which then produces the harmonics.     The amount of conducted noise produced is also very dependent on the load characteristics, so one application may produce significantly different conducted noise levels than another.  FYI, som ethought might be that a "zero-crossing" turn on type SSR produces less of these harmonics than an "instantaneous" turn-on tyep SSR.  Both types gate and act essentially identical when the SSR is continuously on.     Granted, that in some applicaitons the EMC harmonics is prohibitive, but there are still many positive advantages to the use of SSR's over EMR's and if those advantages are needed they may tip the scales.   (Reference, please see....

                                                                                                                                                         

                                                                                                                                                        http://www.crydom.com/en/Tech/Brochures/handout_US.pdf

                                                                                                                                                         

                                                                                                                                                        Regards,

                                                                                                                                                        Pete B.

                                                                                                                                                        • 73. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                          ankit29030

                                                                                                                                                          hello sir,

                                                                                                                                                           

                                                                                                                                                          we are glad to see someone is out for our help.

                                                                                                                                                           

                                                                                                                                                          i want to make a circuit for automatic on/off of submersible motors based upon instructions given by a microcontroller.

                                                                                                                                                          but the solid state relay i want to use just have a on function.they can be switched from off to on only but cant be switched off by our controller..so tell me any alternate for solid state relay i may use in my project for switching function..

                                                                                                                                                          • 74. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                            PeteB

                                                                                                                                                            Hi.

                                                                                                                                                             

                                                                                                                                                            I'm sure I can help you with your question, but it is a little confusing.  Are you  trying to use a particular solid state relay ?  And is that relay staying ON once it is signaled from the controller even after the controller removes the input signal?   If so, please provide the relay part number, along with your load voltage  (AC or DC), load current, control signal, etc.    I suspect that you are attempting to use an AC output solid state relay on a DC load.   The AC output type SSR will indeed trigger on and power a DC load when commanded, but will not turn OFF by simply removing the input signal.   You would have to disconnect the load voltage completely in this case to get the system to shut-off.   This is due to the fact that AC output SSR's utilize power SCR's which once triggered (gated) ON, will stay ON until the current they are conducting goes to zero.  (The normal AC line voltage sine wave provides this function every half-cycle).      DC output SSR's  typically use Bi-polar transistor or power MOSFET technology which will turn-off load current through removal of the base or gate signal.

                                                                                                                                                             

                                                                                                                                                            Solid State Relays are different from most mechanical relays can in most cases be used for both AC or DC loads (with proper de-rating).    With SSR's one MUST use an AC output SSR for AC loads, and a DC output SSR for DC loads.  

                                                                                                                                                             

                                                                                                                                                            Pete B.

                                                                                                                                                            • 75. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                              ankit29030

                                                                                                                                                              dear sir,

                                                                                                                                                               

                                                                                                                                                              my requirements are:-

                                                                                                                                                               

                                                                                                                                                              1--upon signalling from microcontroller the relay should become on to take an ac load of voltage 240-440 volts.

                                                                                                                                                               

                                                                                                                                                              2--upon signalling from mc the relay should become off..

                                                                                                                                                               

                                                                                                                                                              3--it should be dc controlled..an load current is upto 50 amps..

                                                                                                                                                               

                                                                                                                                                              if my requirements are not fulfilled by relay so plz suggest me another device than relay...

                                                                                                                                                               

                                                                                                                                                              the basic idea is to on a submersible motor and off it accouding to instruction given by microcontroller..

                                                                                                                                                              • 76. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                PeteB

                                                                                                                                                                Hi Ankit.

                                                                                                                                                                 

                                                                                                                                                                Your description of the operation still needs some clarification.   From your sequence #1 and #2, it sounds like you want the relay to turn on with a control pulse,   stay on when that pulse is gone,  and then when another pulse is provided to the relay input, it should go off.  Correct?   If so, that means you need a latching type relay that changes state each time an input pulse is given.    That is a type function available with latching mechanical relays, or by using another type of control to a solid state relay between your controller and the .  But unfortunately, it is not available built in to a solid state relay, so I am sorry, but I have no offer for you.   Please let me know if I interpret your description of the desired operation correctly.

                                                                                                                                                                 

                                                                                                                                                                Pete B.

                                                                                                                                                                • 77. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                  mnoble

                                                                                                                                                                  Probably way too late for NKBHATI, but it's possible to switch an AC load on or off very quickly at ANY phase angle by using "back to back" MOSFETs, something that's not possible with the thyristors used in SSRs.

                                                                                                                                                                   

                                                                                                                                                                  You connect the sources of 2 N-channel MOSFETs together, the drain of one MOSFET to the power supply and the drain of the other MOSFET to the load. By applying a positive DC voltage to the gates of the MOSFETs (with respect to the sources), they will both turn on. When the gates are pulled to the same potential as the sources, they turn off. The reason you need "back to back" MOSFETs is due to the "body" diodes in the FETs, which will conduct when a reverse voltage is applied.

                                                                                                                                                                   

                                                                                                                                                                  To achieve the(isolated DC voltage for driving the gates I used a spare winding on a transformer with rectifier capacitor 78L12 voltage regulator Then I used a  FOD3180FOD3180 optocoupler to drive the gates from a microcontroller

                                                                                                                                                                  • 79. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                    amshahid

                                                                                                                                                                    hi

                                                                                                                                                                    i have an SSR output(for AC load) of a controller but its current rating is 2A which is not as per my requirement. my requirement is 5A. can i connect another SSR of 5A at the output of already installed SSR for 2A load. means is it possible to drive an SSR with the output of SSR. or some other solution please.

                                                                                                                                                                    regards

                                                                                                                                                                    abdul majeed

                                                                                                                                                                    • 80. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                      PeteB

                                                                                                                                                                      Hi Abdul.

                                                                                                                                                                       

                                                                                                                                                                      If the existing 2 amp SSR cannot be replaced with a higher current rated SSR,  your proposal to drive a higher capacity SSR with the existing SSR is certainly possible.  There are a couple of things to be carefull with though, to do this successfully.

                                                                                                                                                                       

                                                                                                                                                                      1.  The input type  and voltage rating of the higher capacitiy SSR must be compatible with the output of the existing SSR.  You note that the existing SSR is of the AC output type, so an AC input type is called for.   Just be sure the voltage range of that input matches what you are switching with the existing SSR.

                                                                                                                                                                       

                                                                                                                                                                      2.  You will of course have to supply the AC voltage to the existing SSR output to be switched through it to the additional SSR, essentially using the input of the additional SSR as the "load" switched by the exsting SSR.

                                                                                                                                                                       

                                                                                                                                                                      3.  You will need to consider what the "minimum load current" specification requirement is for the existing SSR to ensure it switches properly, and be sure that the input current drawn by the higher rated SSR meets that minimum.   Typically, the minimum load current spec for SSR's may be on the order of 25 - 50 ma or more, while the input circuit current draw for the additional SSR may only be 8 to 15 ma.  In that case you will need to supply an additional "load" paralleled across the higher capacity SSR input to meet the minimum load spec of the existing SSR.   One way to do this would be to use a suitably sized resistor connected in parallel across the new SSR input to draw the additional current.    Be sure to figure the wattage needed for that resistor.    Another alternative would be to connect a low wattage lamp instead of a resistor.   As long as that lamp draws at least the minimum current, you will then also have an "indicator" that the SSR circuit is in operation.

                                                                                                                                                                       

                                                                                                                                                                      4.  As with most SSR's operated around 5 amp or above, you need to consder what heatsinking is needed.   This will be found in the datasheet for the extra SSR you will be using.  It won't likely be much heatsinking needed, but be sure to check out the specifications on that SSR.

                                                                                                                                                                       

                                                                                                                                                                      Regards,

                                                                                                                                                                      Pete B.

                                                                                                                                                                       


                                                                                                                                                                      • 81. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                        amshahid

                                                                                                                                                                        Thanx so much Mr. Pete B.

                                                                                                                                                                         

                                                                                                                                                                        u shared very useful and detailed information regarding my problem. i will try ur valuable suggestions and i hope my problem will be solved. otherwise i will consult u again

                                                                                                                                                                         

                                                                                                                                                                        Thanx & Best Regards

                                                                                                                                                                        abdul majeed

                                                                                                                                                                        • 82. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                          crschmidtiii

                                                                                                                                                                          Sir:

                                                                                                                                                                           

                                                                                                                                                                          I have a very basic question, one that I am somewhat embarrassed to post.  But, I need an answer, so here goes...

                                                                                                                                                                           

                                                                                                                                                                          I want to have the ability to turn off my hot tub during peak electrical hours.  The tub draws 50 amps at 240 volts, mostly for the heating element.  The tub has a motor (pump) as well.  I have a PLC that can drive the relay "coil" (24 volts, dc), but I find it hard to believe that any solid state device could handle switching the heavy output current required.  I have no experience with solid state relays, I have always used old fashioned relays and contactors.  If a solid state relay will do the job, can you make a recommendation for me? 

                                                                                                                                                                           

                                                                                                                                                                          I appreciate all the help you provide to all!

                                                                                                                                                                           

                                                                                                                                                                          Thanks

                                                                                                                                                                          Chuck

                                                                                                                                                                          • 83. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                            PeteB

                                                                                                                                                                            Hi Chuck.

                                                                                                                                                                             

                                                                                                                                                                            Actually, your question is not all that basic, and I'm glad you asked !

                                                                                                                                                                             

                                                                                                                                                                            A solid state relay can indeed handle the 240 Vac / 50 amp load.     Matter of fact we have SSR's with ratings up to 660 Vac / 125 amp !   The successful use of an SSR mainly depends on the correct selection of the SSR along with the appropriate heatsinking needed for the load current and ambient temperature where the SSR / Heatsink will be located.  Keep in mind tha tas with all solid state relays, a 50 amp load current through an SSR will dissipate about 50 watts of heat in it that needs to be removed via heatsinking.

                                                                                                                                                                             

                                                                                                                                                                            If your actual current load is 50 amp, then i'd suggest going with the next higher rated current range, (for our Series 1 240 Vac products, that'd be a 75 amp rated... D2475).   That unit can handle up to 75 amp, and accept a DC input ("coil") voltage of anything between 3 and 32 Vdc while only pulling 12 ma or so from your 24 Vdc control.     Since your load is mostly resistive (the heaters), this zero-cross turn-on version will be fine for your load.  If your load is actually less than 50 amp, then take a look at the D2450.

                                                                                                                                                                             

                                                                                                                                                                            http://www.crydom.com/en/Products/Catalog/s_1.pdf

                                                                                                                                                                             

                                                                                                                                                                            On that datasheet, page 5, you'll see the derating / heatsinking curves.   This is the way they work to help you determine heatsinking.....   If your load current is actually 50 amp, and the maximum ambient temp surrounding the SSR and heatsink (in a control box, or where the existing EMR is located), will never exceed a maximum of 40 C, then for 50 amp you would need at least a 1.0 degC/W rated heatsink.  If the ambient would max out at say... 60 degC, then you'd need at least a 0.7 degC/W rated heatsink.   For a comparison of what the heatsinks look like here's a link...

                                                                                                                                                                             

                                                                                                                                                                            http://www.crydom.com/en/Products/Catalog/AdvancedWebPage.aspx?CategoryText1=SSR%20Accessories

                                                                                                                                                                             

                                                                                                                                                                            Click on the "HS Series Heatsinks" picture and you'll get the entire list of our accessory heatsinks.

                                                                                                                                                                             

                                                                                                                                                                            There are 2 "Crydom Tech Lab" videos that should help you out covering heatsinking and how operating conditions affect the selection and use of SSR's...

                                                                                                                                                                             

                                                                                                                                                                            http://www.crydom.com/en/Tech/TechLab.shtml

                                                                                                                                                                             

                                                                                                                                                                            ...along with a few "Tech-tip" articles on heatsinking and selection in the Tech library....

                                                                                                                                                                             

                                                                                                                                                                            http://www.crydom.com/en/Tech/Tips.shtml

                                                                                                                                                                             

                                                                                                                                                                            This is a great application. Please let me know if you've further questions as you review the info on the links.

                                                                                                                                                                             

                                                                                                                                                                            Regards,

                                                                                                                                                                            Pete B.


                                                                                                                                                                            • 84. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                              mlugo8560

                                                                                                                                                                              Hi Pete,

                                                                                                                                                                               

                                                                                                                                                                              What is the best way to test a DC to DC SSR? I have researched everywhere and all of the examples are for Ac to DC SSRs. I have a 5A, 250VDC high voltage, transformer, isolated SSR and need to test operability and current carrying capability. Any suggestions.

                                                                                                                                                                               

                                                                                                                                                                              Thanks,

                                                                                                                                                                               

                                                                                                                                                                              Michelle

                                                                                                                                                                              • 85. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                phoenixsilverbird

                                                                                                                                                                                Hi Pete

                                                                                                                                                                                 

                                                                                                                                                                                I am trying to operate a solenoid locking mechanism through a raspberry pi.

                                                                                                                                                                                 

                                                                                                                                                                                My plan is as follows - use a 12V DC power supply through a relay to power the 12V relay. Using 3.3V from the raspberry pi GPIO pins to control the relay.

                                                                                                                                                                                 

                                                                                                                                                                                As I live in the UK, I am struggling to find 'DC to DC' relays. For some reason, I don't understand how all these products use a DC input and DC control voltage, but the output is AC (???)

                                                                                                                                                                                 

                                                                                                                                                                                See this link for an example: http://www.amazon.co.uk/Solid-State-Relays-Output-24-380V/dp/B009SXHJD6/ref=sr_1_5?ie=UTF8&qid=1395777340&sr=8-5&keywords=relay

                                                                                                                                                                                 

                                                                                                                                                                                How on earth can the DC input be converted to AC just by the relay?

                                                                                                                                                                                 

                                                                                                                                                                                Thanks,

                                                                                                                                                                                phoenix

                                                                                                                                                                                • 86. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                  PeteB

                                                                                                                                                                                  Hi Michelle.

                                                                                                                                                                                  I'll first assume that you have on hand a DC input / DC output solid state relay, (SSR). Keep in mind that AC output SSR's cannot be used for switching DC loads.

                                                                                                                                                                                   

                                                                                                                                                                                  Testing a DC input / DC output Solid State Relay is basically the same as testing a DC input / AC output solid state relay except that you need to correctly hook-up a nominal DC power source and load to the SSR.   Although you would get some sort of indication of operation on a MOSFET output SSR with a simple VOM across the output checking for resistance, the most consistent and certain indication is to do the test under load.  I first suggest you take a look at this short article from our website (www.crydom.com) describing DC output SSR's and the correct wiring.  the polarity must be followed both for actuating the input, and also on the output side.   The article also describes how to protect the SSR from "back-EMF" pulses caused by any inductive characteristic of the load and / or wiring in the system.  This is important to consider.

                                                                                                                                                                                   

                                                                                                                                                                                  http://www.crydom.com/en/Tech/Tips/DC%20relays-technical%20guidelines.pdf

                                                                                                                                                                                   

                                                                                                                                                                                  After that, it's simply a matter of using the correct load to pull the desired testing current you want to verify can be handled and applying the correct input signal per the SSR you have to actuate it.  Beside checking the switching of the load, you can verify the voltage drop across the SSR output with a DC voltmeter, and check it against the SSR specification.   That specification is usually given in a resitance value, (Rds-on) and is typically mohms.  So your voltage drop is dependent on the Rds-on value with the test load current.

                                                                                                                                                                                   

                                                                                                                                                                                  Regards,

                                                                                                                                                                                  Pete B.


                                                                                                                                                                                  • 87. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                    PeteB

                                                                                                                                                                                    Hi Phoenix.

                                                                                                                                                                                    First, a DC input / AC output solid state relay does not convert DC to AC.  It is simply a relay, a “remotely” operated switch.     DC input and DC control voltage are sometimes used interchangeably, and are the same thing, they both pertain to the input side of the SSR.    

                                                                                                                                                                                     

                                                                                                                                                                                    The input side is TOTALLY electrically isolated from the output side, passes a signal across an optical barrier, and then switches on the power semiconductors on the output side to power the load.   With an AC output SSR, the power semiconductors are SCR's, with a DC output SSR they are typically power MOSFET's but also can be bi-polar treansistors or IGBT's.    This is the same principle as a mechanical relay which uses a low current through a coil, producing a magnetic field that then actuates the switch contacts on the output side completing the circuit. 

                                                                                                                                                                                     

                                                                                                                                                                                    The “Tech Tip”  articles on DC SSR’s and “Solid State Relays- the inside story” should help your understanding.  Just replace the power SCR’s shown in the AC output SSR diagrams with a power MOSFET and that should give you the picture. 

                                                                                                                                                                                     

                                                                                                                                                                                    http://www.crydom.com/en/Tech/Tips/DC%20relays-technical%20guidelines.pdf

                                                                                                                                                                                     

                                                                                                                                                                                    http://www.crydom.com/en/Tech/Tips/SSR%20the%20inside%20story.pdf

                                                                                                                                                                                     

                                                                                                                                                                                    Additionally, the block circuit diagram on a DC output SSR datasheet will also show you what I’m speaking of.  Take a look at this datasheet for this DC output SSR in our EL series….

                                                                                                                                                                                     

                                                                                                                                                                                    http://www.crydom.com/en/Products/Catalog/e_l_dc.pdf

                                                                                                                                                                                     

                                                                                                                                                                                    For your application you can browse the different panel mount DC output SSR’s  to see what voltage and current ranges are available here….

                                                                                                                                                                                     

                                                                                                                                                                                    http://www.crydom.com/en/Products/Catalog/AdvancedWebPage.aspx?CategoryText1=Panel%20Mount&CategoryText2=DC%20Output%20SSR&SBCatPage=

                                                                                                                                                                                     

                                                                                                                                                                                    There are also PCB mount DC output SSR’s and Din-rail mount SSR’s in our product line too.  Just be sure to look for “DC output” SSR’s.

                                                                                                                                                                                     

                                                                                                                                                                                    Since you're planning on switching a locking mechanism which is likely a solenoid, (inductive type load), please be certain to place a reverse biased protection diode across your load, (not across the SSR.  Reference the datasheet for the particular SSR and the figure A in the DC SSR tech tip for details.)

                                                                                                                                                                                     

                                                                                                                                                                                    I hope you find the information useful.

                                                                                                                                                                                     

                                                                                                                                                                                    Pete B.

                                                                                                                                                                                    • 88. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                      mlugo8560

                                                                                                                                                                                      Thank you very much for the information. I have one last question, what type of load can I use for a 250vdc 5amp SSR. I have a teledyne 603-4 relay.

                                                                                                                                                                                       

                                                                                                                                                                                      THanks

                                                                                                                                                                                      MIchelle

                                                                                                                                                                                      • 89. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                        PeteB

                                                                                                                                                                                        Hi Michelle.

                                                                                                                                                                                         

                                                                                                                                                                                        Keep in mind that on the relay you note, 5 amp  and 250 Vdc are the absolute maximum ratings of that relay.   To safely run 5 amps through it, the relay will need to be mounted on a suitable heatink per the derating curves in its datasheet.  And also, don't forget the reverse biased diode across the load as is usually shown in the datasheet.

                                                                                                                                                                                         

                                                                                                                                                                                        As for your load, for a basic operational test you don't particulary need to run the relay at the full rated load current and voltage to verify the operation, but you ceratinly can do so if you like.   For my own testing purposes here in our lab, unless I'm studying the operation of the SSR characteristics with a specific unique load,  a general purpose and economical test load can be constructed using appropriate wattage and voltage rated tungsten lamps in parallel / series combinations.     The lamps provide both a visual indication, and a nice little current surge inrush when the filaments are cold.    For example, a 150 Watt / 120 Vac lamp can be used at 120 Vdc and will draw about 1.25  amp.   Paralleling 4 of them will make a 5 amp load.   If you want to test the relay at 240 Vdc, then add a second set of 4 paralleled lamps in series with the other paralleled set.

                                                                                                                                                                                         

                                                                                                                                                                                        You can utilize power resistors or a set of "Cal-rod" heaters in the same manner, but they don't provide a "surge" at startup.    Just figure the total resistance needed for 5 amp @ 250 Vdc ( ...50 ohm), and  be sure to figure your wattage correctly.   Here you'd be looking at 1250 Watts total.    DC motors are also useful for loads, but unless they're mechanically loaded down, they may not draw the expected current.

                                                                                                                                                                                         

                                                                                                                                                                                        Regards,

                                                                                                                                                                                        Pete B.

                                                                                                                                                                                        • 90. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                          amshahid

                                                                                                                                                                                          Hi Mr.Pette B

                                                                                                                                                                                          i have already discussed a prob with u that an SSR of higher rated current can be driven from an SSR of low rated current. u replied its certainly possible. ur detailed answer is at serial #80 dated March 7, 2014. my existing SSR is installed in a controller which not replaceable. it is DC input and AC output type. so, as per ur advice  an AC input SSR can be driven from the existing SSR. normally there are available DC input SSR's in the market. but i have arranged an AC input (30~250V AC) SSR.

                                                                                                                                                                                          1. Now my question is that How many AC volts should i use to switch from the existing SSR and drive the higher rated SSR. will it be safe to use 220 V AC for this purpose. or i should reduce the AC Volts. how many AC Volts can be switched successfully?

                                                                                                                                                                                          2. should i switch the phase or neutral.

                                                                                                                                                                                               will be waiting for ur advice pls

                                                                                                                                                                                               regards

                                                                                                                                                                                               abdul majeed

                                                                                                                                                                                          • 91. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                            awebster

                                                                                                                                                                                            Hi Pete

                                                                                                                                                                                            I would like to build a light dimming system which involves over 1000 light fixtures divided up in multiple circuits. I can not seem to be able to fine a four pole SSR with 0 to 10 volt DC input which equals 0 to 100% light dimming control. Can you send a link to a SSR that can be used for light dimming and has 4 inputs and 4 outputs and can handle 20 amps at 240vac? Much appreciated. A sales link would be great...  -Andrew

                                                                                                                                                                                            • 92. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                              PeteB

                                                                                                                                                                                              Hi Abdul.  

                                                                                                                                                                                              For your question #1, since the input of the external SSR you want to use is rated from 30 – 250 Vac, any voltage within that input range will be within the input specifications and would control that SSR.  Do not exceed the input specification range of 250 Vac, nor go below the lower end limit, 30 Vac).      Of course, you need to be within the output switching specification range of your internal SSR also.

                                                                                                                                                                                              For question #2, a solid state relay can switch either the “Hot” or “Neutral” line, there is no difference to the SSR, but most users tend to follow the convention used with mechanical switches in that the relay is in the “hot” line.

                                                                                                                                                                                              Regards,

                                                                                                                                                                                              Pete B

                                                                                                                                                                                              • 93. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                PeteB

                                                                                                                                                                                                Hi Andrew.

                                                                                                                                                                                                Unfortunately, I don’t believe a 4 pole phase angle control SSR that utilizes a direct 0 – 10 Vdc analog input exists anywhere, and although we many 2 channel independent input models, those are “on-off” function SSR’s.      Back to your need though, Crydom does offer 2 single pole phase angle control SSR series that meet your control requirement of 0 – 10 Vdc, the LPCV series….

                                                                                                                                                                                                 

                                                                                                                                                                                                http://www.crydom.com/en/Products/Catalog/l_pcv.pdf

                                                                                                                                                                                                 

                                                                                                                                                                                                …available in 15 amp through 110 amp capacity,   and the MCPC series…

                                                                                                                                                                                                 

                                                                                                                                                                                                http://www.crydom.com/en/Products/Catalog/m_cpc.pdf

                                                                                                                                                                                                 

                                                                                                                                                                                                …covering 25, 50, and 90 amp capacities.   Beyond those 2, there is also the 10PCV series…

                                                                                                                                                                                                 

                                                                                                                                                                                                http://www.crydom.com/en/Products/Catalog/p_cv.pdf

                                                                                                                                                                                                 

                                                                                                                                                                                                …with 15 to 90 amp capability that does not require any additional logic type power source on the control side.   However, to do this the PCV series control range is 2 to 10 Vdc for 0 – 100% phase angle control.   It needs that minimum threshold of 2.0 Vdc to be able to operate the unit.

                                                                                                                                                                                                 

                                                                                                                                                                                                Regarding a sales link, as one of our distribution partners, Newark / Element 14 can handle volume quoting quite easily!    As needed, our full contact information including distribution, sales representatives, sales support, technical support, can be found on the Crydom website.. 

                                                                                                                                                                                                 

                                                                                                                                                                                                http://www.crydom.com/en/

                                                                                                                                                                                                 

                                                                                                                                                                                                …under “Contact Us”.

                                                                                                                                                                                                 

                                                                                                                                                                                                Regards,

                                                                                                                                                                                                Pete B.

                                                                                                                                                                                                • 94. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                  srcnist

                                                                                                                                                                                                  Hello Mr.Pete,

                                                                                                                                                                                                   

                                                                                                                                                                                                  I have a question. I am using many ssrs for many applications. I just want to understand sth. When i need ssr (for ex. 50A) the sellers suggest me to buy min. 1,5-2 times larger current ranged ssr. if my load current is 50A, and my load is enductive, they offer me 80-100A ssr. if my load is capasitive, they offer me 6-7 times larger range ( 300-400A ssr for 50A load). why i can not cross the same value which is writing on the ssr's label? they are telling me that value is for peak current... is that true?

                                                                                                                                                                                                  • 95. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                    PeteB

                                                                                                                                                                                                    Hi Sercan.

                                                                                                                                                                                                    I can understand suggesting at least a small amount of headroom for an application and not pushing a 50 amp rated SSR right to its specification limit by running exactly 50 amp load current, so moving to the next available rating up, (75 amp in some cases), would be prudent.     Perhaps there is some consideration they are making in their suggestions due to factors such as very elevated ambient temperatures or less than adequate heatsinking? 

                                                                                                                                                                                                    As for capacitive loads, they are likely concerned with the in-rush / surge current that the capacitive load could possibly draw for the initial “on” cycle if fully discharged, (especially if switched with an “instantaneous” type SSR rather than a zero-cross type), but that should be easily covered by the single cycle surge rating of the SSR if they  are shown on the datasheets.

                                                                                                                                                                                                    Crydom has always published single cycle surge ratings and we're expanding that in our newer SSR series to show surge curves extending up through 10 seconds.  As an example, our Crydom CWD2450, (50 amp / 280 Vac SSR), has a single cycle surge rating of 850 Apk, well over 17x its full RMS current rating of 50 amp.    The current printed on the SSR label is typically the steady state rated, RMS current.  

                                                                                                                                                                                                    Regards,

                                                                                                                                                                                                    Pete B.

                                                                                                                                                                                                    • 96. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                      testjack

                                                                                                                                                                                                      I am considering building an antenna switch to select multiple antennas to multiple receivers and tranceivers. Will solid state relays work with RF?  What would be the maximum power they could handle from a transmitter? Legal limit is 1000 watts?

                                                                                                                                                                                                       

                                                                                                                                                                                                      Thanks in advance

                                                                                                                                                                                                       

                                                                                                                                                                                                      Jack

                                                                                                                                                                                                      • 97. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                        ptiago

                                                                                                                                                                                                        Hi Pete,

                                                                                                                                                                                                         

                                                                                                                                                                                                        First of all thanks for your time and shared knowledge.

                                                                                                                                                                                                        After reading a few questions, it seems possible to build a web based wizard (multiple QA) to help the SSR selection ;-).

                                                                                                                                                                                                         

                                                                                                                                                                                                        Let's start with requirements:

                                                                                                                                                                                                         

                                                                                                                                                                                                        1) SSR always closed (even if the SSR + electronics have no power)

                                                                                                                                                                                                        2) Control Input is DC 5V

                                                                                                                                                                                                        3) Load DC (7.5 - 9V / 3 A)

                                                                                                                                                                                                        4) Load type DC motors and microcontroller.

                                                                                                                                                                                                         

                                                                                                                                                                                                        I would like to build a controlling circuit using a SSR when is powered ON from a different source (plug in charger)  will switch off the independent circuit battery powered, when the controlling circuit (SSR) is unplugged the SSR keeps the circuit (load) closed.

                                                                                                                                                                                                         

                                                                                                                                                                                                        Is this possible using a SSR ?

                                                                                                                                                                                                         

                                                                                                                                                                                                        Thank you

                                                                                                                                                                                                         

                                                                                                                                                                                                        Regards,

                                                                                                                                                                                                        Pedro

                                                                                                                                                                                                        • 98. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                          fuba

                                                                                                                                                                                                          Hi Pete,

                                                                                                                                                                                                          excuse me for my english.

                                                                                                                                                                                                          Can you help me for this problem.

                                                                                                                                                                                                          i have a webserver based on wiznet W5100 Ethernet chip.

                                                                                                                                                                                                          i have 2 mechanical relay almost near the Ethernet chip and i can't distance them.

                                                                                                                                                                                                          when I connect a Light Bulb(or anything)running at 220V to relay output terminal It just turns ON once and then w5100 hangs and I will restart it manually.

                                                                                                                                                                                                          i noticed that if i away 220v wires from cat5 the situation is much better.and at this status it may hangs after 20 or 30 times relay turn ON/OFF.

                                                                                                                                                                                                          It sounds like a transient gets coupled into the cat5 then finds its path through the Ethernet chip.

                                                                                                                                                                                                           

                                                                                                                                                                                                          Is it possible using SSR relays solve the problem?

                                                                                                                                                                                                           

                                                                                                                                                                                                          thank you.

                                                                                                                                                                                                          • 99. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                            shahzad

                                                                                                                                                                                                            Hi i have a question.

                                                                                                                                                                                                            i need some solid state relay containing both normally open terminal and normally close terminal and it works upto 150VDC or above.

                                                                                                                                                                                                            Any good suggestion will be appreciated Thanks

                                                                                                                                                                                                            • 100. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                              mattb5906

                                                                                                                                                                                                              Do you know of any solid state relays that would meet the following specification? Or have they still not got the operational range?

                                                                                                                                                                                                              DC control voltage: 12V or less

                                                                                                                                                                                                              Load type: AC and DC resistive (FET based?)

                                                                                                                                                                                                              AC load: 20V to 260V

                                                                                                                                                                                                              DC load: 6V to 60V

                                                                                                                                                                                                              Load current: up to 2A

                                                                                                                                                                                                               

                                                                                                                                                                                                              All the ones i have found so far are limited to high voltage loads or AC only

                                                                                                                                                                                                               

                                                                                                                                                                                                              Thanks

                                                                                                                                                                                                              • 101. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                hjalli

                                                                                                                                                                                                                Hello Pete

                                                                                                                                                                                                                 

                                                                                                                                                                                                                Im wondering what coses the SSR to heat up during operations... Is it the speed of the switching? or is it mainely the size of the current flowing throug the transistor? 

                                                                                                                                                                                                                 

                                                                                                                                                                                                                kind regards

                                                                                                                                                                                                                Hjalli

                                                                                                                                                                                                                • 102. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                  alecz

                                                                                                                                                                                                                  Hi Pete,

                                                                                                                                                                                                                   

                                                                                                                                                                                                                  Since AC SSR uses SCRs for its output control, can I use this type of SSR to control DC load for as long as I have to make sure that the DC load supply is zero AND the AC SSR control voltage is zero if I want to turn this OFF ?

                                                                                                                                                                                                                   

                                                                                                                                                                                                                  Regards,

                                                                                                                                                                                                                   

                                                                                                                                                                                                                  Alex

                                                                                                                                                                                                                  • 103. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                    itznaidu

                                                                                                                                                                                                                    Dear Sir,

                                                                                                                                                                                                                                I am using relays at my home for switching inductive and resistive loads. I am presently using EMR. and it is working fine. I was suggested to use SSR. I studied about them. One query I had was, let's say I am using the SSR for a plug point at my home, at home anything can be connected to that plug point. So should I stick with EMR or SSR for this kind of an application.

                                                                                                                                                                                                                    • 104. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                      PeteB

                                                                                                                                                                                                                      Hi Jack.  I apologize for not seeing your question from 5 months ago !   There must have been a setting change in my EL14 account that prevented a notification e-mail from being sent to me.

                                                                                                                                                                                                                       

                                                                                                                                                                                                                      Regarding the RF question, sorry but no.  A typical general purpose SSR (either AC or DC swtching), is not suited to switch RF loads.   RF switching is a very specialized science that Crydom has not chosen to participate in.

                                                                                                                                                                                                                       

                                                                                                                                                                                                                      Regards,

                                                                                                                                                                                                                      Pete B.

                                                                                                                                                                                                                      • 105. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                        PeteB

                                                                                                                                                                                                                        Hi Pedro.  Please accept my apologies for not seeing your question for this length of time.

                                                                                                                                                                                                                         

                                                                                                                                                                                                                        Matter of fact, we do have a parametric search tool on the Crydom website that would indeed steer you to a normally closed DC switching SSR.

                                                                                                                                                                                                                         

                                                                                                                                                                                                                        http://www.mectronic.com/scripts/crydom/param/Main.asp

                                                                                                                                                                                                                         

                                                                                                                                                                                                                        The DC60 series, (part number DC60S3-B), will handle a 3 amp load in a normally closed manner. 

                                                                                                                                                                                                                         

                                                                                                                                                                                                                        http://www.crydom.com/en/Products/Catalog/d_c60.pdf

                                                                                                                                                                                                                         

                                                                                                                                                                                                                        However, for your application of switching between 2 separate power sources, be sure to sketch into your circuit diagram a reverse biased diode acros the SSR output terminals (this reverse diode is internally included within the DC output SSR), and is shown in the block circuit diagram of the SSR on it's datasheet.   That reverse diode sometimes "surprises" the designer in an unexpected manner if they fail to take it into consideration in their application.

                                                                                                                                                                                                                         

                                                                                                                                                                                                                        Regards,

                                                                                                                                                                                                                        Pete B.

                                                                                                                                                                                                                        • 106. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                          PeteB

                                                                                                                                                                                                                          Hi Fuba.   If you're still working on this issue after my 4 month absence of seeing the questions, I will try to help, but I'm not an EMI type expert.

                                                                                                                                                                                                                           

                                                                                                                                                                                                                          I doubt that an SSR would solve your problem as you describe, since the 220V load current is the likely root cause.   Switching with an SSR will not change that load current in any significant manner, and with the slight additional "continuous turn-on spike" that any AC output SSR generates at each AC half cycle, it may worsen the situation.

                                                                                                                                                                                                                           

                                                                                                                                                                                                                          Regards,

                                                                                                                                                                                                                          Pete B.

                                                                                                                                                                                                                          • 107. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                            PeteB

                                                                                                                                                                                                                            Hi Amir.

                                                                                                                                                                                                                             

                                                                                                                                                                                                                            As I've stated for the previous inquiries, I apologize for not seeing your question from 3 months ago.  I hope I now have that issue resolved.

                                                                                                                                                                                                                             

                                                                                                                                                                                                                            For your question, a normally closed DC output SSR is not very common (our DC60x - B series covers up to 60 Vdc and up to 7 amp).   However I am not aware of a power SSR that contains both a normally closed and normally open (SPDT type configuration).   You can of course create an SPDT configuration with 2 separate SSR's, but within one package, I'm sorry that I have no suggestions for you.

                                                                                                                                                                                                                             

                                                                                                                                                                                                                            Pete B..

                                                                                                                                                                                                                            • 108. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                              PeteB

                                                                                                                                                                                                                              Hello Matt.  I'm sorry that I failed to see your message from 2 months ago !  

                                                                                                                                                                                                                               

                                                                                                                                                                                                                              You are correct in that most power SSR's are either AC or DC output switching, but not capable of both.  There are small FET based SSR's, (i.e. photomos types etc.) that have that function, but they're typically limited to at most several hundred ma loads and limited in their voltage.  

                                                                                                                                                                                                                               

                                                                                                                                                                                                                              You can utilize 2 separate DC power FET type output SSR's to perform that function, simply by wiring their outputs in "inverse" series and paralleling the inputs together.  This solution does become a bit costly and space hungry though.     The output voltage would need to be selected to handle the maximum peak AC line voltage, so 400 Vdc SSR's would be required.   The Crydom D4D07 (400 Vdc / 7 amp rated), would support your list of parameters.

                                                                                                                                                                                                                               

                                                                                                                                                                                                                              Regards,

                                                                                                                                                                                                                              Pete B.

                                                                                                                                                                                                                              • 109. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                PeteB

                                                                                                                                                                                                                                Hi Hjalmar.

                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                With an AC switching SSR using power SCR's or a Triac, the heating is created simply by the forward voltage drop of the semiconductor SCR's, (typically 1.2 - 1.4 Vpk), so that comes out to basically 1 watt of dissipation per load amp switched.

                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                On a DC output SSR using power FET's, the dissipation is created from 2 factors.   The main heat generator is the "Isq*R" loss drop across the FET depending on the Rds-on value  (typically in mohms) at the actual load current..   There is also a switching speed factor that can come into play if the DC SSR is switched very rapidly, (i.e. PWM switching).    If the SSR is not switched often, (I'm speaking of something less than once per second), that switching speed factor is really not a factor in the total heating.

                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                Regards,

                                                                                                                                                                                                                                Pete B.

                                                                                                                                                                                                                                • 110. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                  dixieanray

                                                                                                                                                                                                                                  I want to remote control the field winding on a welding generator.

                                                                                                                                                                                                                                  It is a shunt wound DC generator using a comutator. It's max current is around 750 amps

                                                                                                                                                                                                                                  The feild winding runs 3.5 amps at 120 vdc. There is considerable inductance.

                                                                                                                                                                                                                                  There is some transformer action coupling the welding arc to the field supply so rf, heavy transients, and long power surges are expected.

                                                                                                                                                                                                                                  I am not sure if phase control would overheat the core. It is large and has forced air cooling.

                                                                                                                                                                                                                                  The winding current does not need to go to zero. A small constant current feed to the coil would enable the scrs to turn on.

                                                                                                                                                                                                                                  A freewheeling diode would avoid inductive kick.

                                                                                                                                                                                                                                  The exciter is also a DC generator with comutator but could be replaced by alernator rectifier.

                                                                                                                                                                                                                                  Is it possible for a SSR to adjust the winding current without the relay being destroyed?

                                                                                                                                                                                                                                  • 111. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                    PeteB

                                                                                                                                                                                                                                    Hi Ray.   I'm not a welding generator expert, so I'll answer your question regarding the SSR.   I see that the field current in a shunt wound DC generator is typically controlled via a variable resistance / rheostat.    Unfortunately we have no DC switching SSR that will linearly "throttle" the 3.5 amp/120 Vdc current.   As for a phase control SSR, those are only suited to switch AC power since the power devices used are inverse parallel SCR's.   If an AC output SSR is used with a DC load application, it will turn on, but won't turn-off until the load current is removed.  I'm very sorry that I can't be of much more help than that to you.

                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                    Pete B.

                                                                                                                                                                                                                                    • 112. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                      PeteB


                                                                                                                                                                                                                                      Hi Alex.  

                                                                                                                                                                                                                                       

                                                                                                                                                                                                                                      Since an AC output type SSR uses power SCR's for the switching devices, once they're gated and conducting they stay conducting until the load current goes to zero.   With an AC load, that happens every half-cycle of the AC frequency, so that is the reason why an AC output SSR can take up to almost 1/2 an AC cycle to turn off once the input signal is removed.

                                                                                                                                                                                                                                       

                                                                                                                                                                                                                                      If an AC output SSR is used with a DC load, you are correct.  The SSR will not turn off until both the input signal and the load current are at zero.   If the input signal is still on, as soon as the load source is re-connected the SCR in the output of the relay will latch back on.   There are a few applications where this feature has been used, but it is not a very common practice.

                                                                                                                                                                                                                                       

                                                                                                                                                                                                                                      Our line of DC output switching SSR's typically use power MOSFET's which will cut the load current as soon as the gate signal (powered from the input of the relay) is removed.

                                                                                                                                                                                                                                       

                                                                                                                                                                                                                                      Regards,

                                                                                                                                                                                                                                      Pete B.

                                                                                                                                                                                                                                      • 113. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                        PeteB

                                                                                                                                                                                                                                        Hello Varma.

                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                        An SSR can be used to switch virtually any load as long as the ratings, specifications, thermal parameters, (i.e. heatsinking), etc. are followed.   Replacing an EMR for a plug point as you describe is a very suitable use for an SSR.

                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                        As for the type of loads to be switched..  (resistive, inductive, capacitive), the guidline is that the zero-crossing type of SSR is best for switching capacitive type loads that can present very low impedance at the moment of turn-on, and also handle resistive loads equally well.       An instantaneous type SSR, (also known as "random turn-on") is well suited for both resitive AND inductive loads.    Since most loads encountered in a home connection are either resistive or inductive, the instantaneous / random type of SSR would be recommended. 

                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                        Regards,

                                                                                                                                                                                                                                        Pete B.

                                                                                                                                                                                                                                        • 114. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                          ziaahmed

                                                                                                                                                                                                                                          Dear Pete,

                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                          Greetings.

                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                          Can you recommend me a SCR relay for my application stated below:

                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                          1.5V DC input controlled 230VAC 0.9A supported Relay

                                                                                                                                                                                                                                          or

                                                                                                                                                                                                                                          3V DC input controlled 230VAC 0.9A supported Relay

                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                          Also do you know of a Bluetooth controlled/Wireless SCR Relay for AC o/P

                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                          Appreciate your response.

                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                          Regards,

                                                                                                                                                                                                                                          Zia

                                                                                                                                                                                                                                          • 115. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                            PeteB

                                                                                                                                                                                                                                            Hi Zia.

                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                            I can supply a couple of Crydom SSR suggestions for your 3 Vdc input / 230 Vac-0.9A output, but a 1.5 Vdc solid state relay is generally not available since the opto-coupler type of isolation typically used in an SSR has about a 1.5 Vdc forward voltage drop to overcome first before input current will flow through the input.

                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                            So, for the 3 Vdc input suggestions....

                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                            PCB mount type  MP240D3MP240D3  CX240D5CX240D5

                                                                                                                                                                                                                                            Panel Mount  CL240D05CL240D05 D24D10

                                                                                                                                                                                                                                            Plug-in  ED24D3ED24D3  CN240A05CN240A05

                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                            A few more choices would open up for you if your input voltage could provide 3.5 or 4.0 Vdc such as the 16 pin DIP type DPA or SDV series the ASO series or panel mount  EL240A5-05EL240A5-05

                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                            Regarding an SSR with built-in Bluetooth control, no, to this point I have not seen one, but with the wide availability of Bluetooth interfaces on the market, I am sure that searching on the web for such an interface that could provide a few milliamp at 3 - 5 vdc when attached to the input of a standard SSR would produce results.

                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                            Interesting request !

                                                                                                                                                                                                                                            Pete B.

                                                                                                                                                                                                                                            • 116. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                              markbzeal

                                                                                                                                                                                                                                              Hi Pete,

                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                              I have an SSR which is 40A 240V AC. Can I use this to switch 24V DC?

                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                              Thanks very much,

                                                                                                                                                                                                                                              Mark Brady

                                                                                                                                                                                                                                              • 117. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                PeteB

                                                                                                                                                                                                                                                Hi Mark.

                                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                                The short answer is no, to switch DC loads with a Solid State Relay you must use a model designed specifically for DC switching. 

                                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                                For the long answer... AC output SSR's utilize Thyristor assemblies (dual inverse parallel SCR's), to switch the load power.  (DC SSR's typically use power FET's, Bi-polar Transistors, or IGBT's).    If used with a DC source and load, once the AC SSR is triggered on,  the conducting SCR will latch on and continue to conduct as long as the load current is above the SCR's holding current, (about 50% of the SSR's minimum load current spec is a good indication of that),  even without an input signal.   This continues until the load current is reduced to zero (or below holding current), or the load circuit is broken by some external means.

                                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                                With all that being said, I am aware of several very successful unique DC applications that intentionally use that SCR characteristic to latch a DC load on without a need to continually apply an input signal.

                                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                                Pete B.

                                                                                                                                                                                                                                                • 118. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                  ziaahmed

                                                                                                                                                                                                                                                  Dear Pete,

                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                  I think you got it wrong.

                                                                                                                                                                                                                                                  O/P is

                                                                                                                                                                                                                                                  230 VAC ) not DC

                                                                                                                                                                                                                                                  0.9 A

                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                  Motor

                                                                                                                                                                                                                                                  Regards,

                                                                                                                                                                                                                                                  Zia

                                                                                                                                                                                                                                                  • 119. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                    PeteB

                                                                                                                                                                                                                                                    Hi Zia.

                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                    All of the SSR part numbers I suggested for your 230 Vac / 0.9 Amp motor load are AC output types and will handle your motor load current.

                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                    PCB mount type  MP240D3MP240D3  CX240D5CX240D5

                                                                                                                                                                                                                                                    Panel Mount  CL240D05CL240D05 D24D10 Sorry this pn should have been D2410

                                                                                                                                                                                                                                                    Plug-in  ED24D3ED24D3  CN240A05CN240A05

                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                    One comment I would add since you mention now that your load is a motor would be to suggest that whichever SSR you consider you should utilize the"Random(sometimes called"Instantaneous turn-on version of the SSR For motor inductive loads the random instantaneous type SSR is best suited Other than the  MP240D3MP240D3 the other part numbers are available with"instantaneous type switching outputs So for them

                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                    CX240D5RCX240D5R  CL240D05RCL240D05R  D2410-10D2410-10  ED24D3RED24D3R CN240A05R

                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                    I may have confused the issue for you a little bit by going into the long discussion about the Input Circuitry (the "coil" voltage), and your requirement of needing to use either a 1.5 Vdc or 3.0 Vdc input.    1.5 Vdc INPUT / CONTROL type SSR's are not generally available.   The control input on all of the parts I noted are DC and require at least 3 VDC to control, but the output of all are definitenly AC output for AC loads.

                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                    I hope this clarifies things.

                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                    Pete B.

                                                                                                                                                                                                                                                    • 120. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                      ziaahmed

                                                                                                                                                                                                                                                      Dear Pete,

                                                                                                                                                                                                                                                       

                                                                                                                                                                                                                                                      Thanks this wonderful. Have a great day.

                                                                                                                                                                                                                                                       

                                                                                                                                                                                                                                                      Regards,

                                                                                                                                                                                                                                                      Zia

                                                                                                                                                                                                                                                      • 122. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                        wintana

                                                                                                                                                                                                                                                        Hi Pete,

                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                        Is it always the case that, in all the SSR's the contact configuration is SPST-NO or SPST-NC as they are all solid state devices which turn on with a control signal?


                                                                                                                                                                                                                                                        Thanks

                                                                                                                                                                                                                                                        Sofie

                                                                                                                                                                                                                                                        • 123. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                          ziaahmed

                                                                                                                                                                                                                                                          Hi Pete,

                                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                          Greetings

                                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                          Can I seek your expert advice on use a SSR Crydom relay for Operating a 12V DC controlled device by controlling it with a 3V DC input.?

                                                                                                                                                                                                                                                          My current requirements are very small less than 1A for msec only.

                                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                          Closest I could only find this one:

                                                                                                                                                                                                                                                          SSR, 3A, 3-60VDC

                                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                          Thanks in advance.

                                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                          regards,

                                                                                                                                                                                                                                                          Zia

                                                                                                                                                                                                                                                          • 124. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                            jacostienstra

                                                                                                                                                                                                                                                            Hi Pete,

                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                            I've have a question about the Crydom solid state relays and a question in general about relays. I'm in the proces of designing a system to control the speed of four single phase 230V AC 0.8A ventilation fan motors. These motors will run 24/7 and are used for a ventilation system so reliability is important. I'm looking at the CKR24/48/60 (10 Amp, random turn-on, 5V DC control voltage) relay series, each fan will have it's own SSR. Can you recommend a relay for this? Should i be looking for the 48/60 series or is the 24 series also suitable (voltage spikes etc)?

                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                            And for the second question, i want to run a mechanical relay (230V AC output) in parallel to the motor for manual override and control by a secondary device. A relay like this one: http://gfinder.findernet.com//assets/Series/384/S19EN.pdf

                                                                                                                                                                                                                                                            Is this possible or would this cause damage to the SSR? An example situation would be that the SSR is not receiving a control pulse anymore and the manual relay is switched on. Or the SSR is still controlled and outputs 120V and the mechanical relay is switched on with 230V AC output.



                                                                                                                                                                                                                                                            Best regards,


                                                                                                                                                                                                                                                            Jaco



                                                                                                                                                                                                                                                            • 125. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                              rbrooks

                                                                                                                                                                                                                                                              Hi,

                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                              I've got a setup using a prox sensor to switch a 5v power source on and off.  That power source is connected to the input of a data acquisition card.

                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                              When using a voltmeter, I get 0 and 4.5v as the relay kicks on and off - If I hook it to the input of my DAQ card, it floats around from 1-4.2v until the relay hits, then it shows 4.5 and sort of holds there or drops off a little upon release.

                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                              Connecting the voltmeter in parallel causes both to work (Meter and DAQ card).  I'm assuming the DAQ card doesn't have enough of a 'load' for the SSR to function correctly.  Is there another option to increase the load?  Bleed resistor?  Remove or reduce the in line resistor?

                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                              Thanks!boeing wiring diagram.jpg

                                                                                                                                                                                                                                                              • 126. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                zac1987

                                                                                                                                                                                                                                                                Hi pete,

                                                                                                                                                                                                                                                                I am working on project to control a temperature of a coolant system so basically I am using PID temperature controller to drive 2 solid state relay to switch my loads on/off, the SSR drive in my PID controller Max current rate is 20mA, let assume that the 2 SSR required more current, could you help me to find external SSR Driver circuit that boost the current from my SSR driver in my PID controller  and this external SSR drive will drive my 2 SSR ( like if you give me a product name so I could purchase it) waiting for your reply with many thanks.

                                                                                                                                                                                                                                                                • 127. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                  marcremi

                                                                                                                                                                                                                                                                  Hello Pete,

                                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                                  I'm looking for a solid state relay where the load is an inductive load (coil of a pneumatic valve).  Reason : the output of our plc has a max output current of 0.5A, therefore we would put a solid state relay between the output of the plc and the valve.

                                                                                                                                                                                                                                                                  I concerns a fast switching valve :  The valve needs to switch on/off  during 3-4 ms every 100ms. The load would consume a max. of 2A at 24VDC.

                                                                                                                                                                                                                                                                  Can you suggest a type which meets these requirements. If there is a better/alternative solution to work with, than a solid state relay , please do not hesitate to mention.

                                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                                  Many thanks.

                                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                                  Regards,

                                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                                  Marc

                                                                                                                                                                                                                                                                  • 128. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                    rbnfrance

                                                                                                                                                                                                                                                                    Hi Pete,

                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                    Not sure if you are still here but I have a question about a problem I am having with some SSR's. I'm sorry that they are not made by Crydom, but I live in China and can't find Crydom SSR's here. The problem is that the SSR's won't switch off at all, even when the LED indicator shows the SSR is off, and even when I disconnect any input contol voltage. The SSR's are not Crydom, but they are not the very cheap chinese ones. I have now tried 4 different SSR's and the same result with all of them. I'm now wondering if it is because the output of the SSR's are not connected to the Heating elements I am using the SSR's to control. Connecting the heating elements is possible but would take 400 litres of water to test it and I wanted to test the SSR function without wasting so much water. They are 3 phase SSR's and I have had an electrician verify that the wiring is correct. Everything I try just results in the 380v passing right through the SSR's.

                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                    Many Thanks in advance.

                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                    Robin

                                                                                                                                                                                                                                                                    • 129. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                      vigneshv

                                                                                                                                                                                                                                                                      hi sir ! i am doing a project which requires the turning on and off of home appliances using arduino and wifi. i am using a relay to perform that switching process. is it possible for the same relay to switch both ac and dc appliances . if not i need the reason to justify sir...

                                                                                                                                                                                                                                                                      kindly help

                                                                                                                                                                                                                                                                      • 130. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                        pep5

                                                                                                                                                                                                                                                                        Hi Pete,

                                                                                                                                                                                                                                                                        I would like to use one 3 phase solid state relay to switch power on for 8 VSD in parallel.

                                                                                                                                                                                                                                                                        The VSD power range is between 0.55 to 2.2 KW. There will not be any motors connected the the VSD's.

                                                                                                                                                                                                                                                                        The duty cycle of the swiching is 30 to 40 sec.

                                                                                                                                                                                                                                                                        This is to test the behaviour of the VSD during power up.

                                                                                                                                                                                                                                                                        What type of solid state can I use, if any ??

                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                        BR

                                                                                                                                                                                                                                                                        Peter

                                                                                                                                                                                                                                                                        • 131. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                          mirmanto

                                                                                                                                                                                                                                                                          Hi Pete,

                                                                                                                                                                                                                                                                          I have a ssr solid state relay with input 3 - 32 VDC, Can the relay produce various voltages, say from 0 - 220V if I connect this input with a 500K 2W potentiometer?

                                                                                                                                                                                                                                                                          Thanks Pete,

                                                                                                                                                                                                                                                                          Regards,

                                                                                                                                                                                                                                                                          Mirmanto

                                                                                                                                                                                                                                                                          • 132. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                            bassemmylove

                                                                                                                                                                                                                                                                            Hello Mr Pete,

                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                            I have an idea of a project to automate a private residential power network. And want to update the existing method of client load control into a method based on solid state relays connected to a computer and controlled/surveyed with a software. I appreciate if you can help me as I couldn't find what I need exactly.

                                                                                                                                                                                                                                                                            The existing one is as follows:

                                                                                                                                                                                                                                                                            • There is a power generator of some 100 or more KVA/ 220 Volts.
                                                                                                                                                                                                                                                                            • multiple clients where the subscription is based on amperage.
                                                                                                                                                                                                                                                                            • each client would subscribe for 5 A, 10 A, 15 A, 20 A etc.- 220V.
                                                                                                                                                                                                                                                                            • each client is responsible to connect himself to the node with a feeding line
                                                                                                                                                                                                                                                                            • the node is in the street, and is a box consisting of circuit breakers. Each circuit breaker corresponds to a client with his relative subscription hence 2.5A, 5A, 10A, 15A... etc. so the node contains as much circuit breakers as the number of clients.
                                                                                                                                                                                                                                                                            • the node is connected to the power generator with one input line

                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                            What I need to do is as follows:

                                                                                                                                                                                                                                                                            • Give up the traditional way of using group circuit breakers with certain amperage allowance, and setup instead a 1-input N-output(N~30 or 40) relay board (I couldn't find this online, and don't know what I need to assemble one)
                                                                                                                                                                                                                                                                            • Connect this relay board to a LAN network directly to a computer at office (I need solution for this as well) so that I would be able to survey the electric load.
                                                                                                                                                                                                                                                                            • I need to be able to configure the each relay output (which corresponds to a client) to a certain amperage, so that for example if the client decides to change the subscription to a higher or lower amperage, I could configure it from my computer software, and thus no need to change the relay itself.
                                                                                                                                                                                                                                                                            • I need the number of client on a node to be flexible. with one feeding line-input and n-outputs.

                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                            Thanks for guiding me, I appreciate it. hope you can help me.

                                                                                                                                                                                                                                                                            Sincerely,

                                                                                                                                                                                                                                                                            Bassem

                                                                                                                                                                                                                                                                            • 133. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                              perl

                                                                                                                                                                                                                                                                              hello there,

                                                                                                                                                                                                                                                                              first off thanks for the great thread, its really helpful.

                                                                                                                                                                                                                                                                              i am a computer engineer. electronics literate' but not electrical, ;0

                                                                                                                                                                                                                                                                              my question is this SSR, can it control two phase lines. for example if i have two AC lines coming into my house, lets say one from the grid and the other from a Solar inverter,

                                                                                                                                                                                                                                                                              can it switch between the two when one is down or low on power (ideal 220 VAC required).

                                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                                              second question, can it control AC ? by this i mean if we have like a 220 VAC line which is not stable for some reasons and is going 400 VAC in times. or maybe 450 VAC with a low of 40 VAC,

                                                                                                                                                                                                                                                                              can this relay control the output to a stable 220 VAC?

                                                                                                                                                                                                                                                                              if this can't, do you have any idea what other device / switch can? more like a surge protector but with stable out.

                                                                                                                                                                                                                                                                              Thanks @pete Bamburak

                                                                                                                                                                                                                                                                              • 134. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                                oscarpepper

                                                                                                                                                                                                                                                                                For a 120 VAC SSR, what is the minimum current required to turn it on? I never see any mention of this spec.

                                                                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                                                                I currently have a 120 VAC mechanical DPST NO relay which when "off" has 120 VAC on the coil and it draws 5 mA causing the relay to hum but not turn on, as this particular relay requires a coil current of 33.3 mA to switch the load of 30 A.

                                                                                                                                                                                                                                                                                Clearly there is a short somewhere in my circuit, but I was thinking rather than troubleshoot it, to place a SSR before the coil of the mechanical relay to trigger it and stop the humming. Would 120 VAC and 5 mA be enough to trigger the SSR or would the SSR ignore it?

                                                                                                                                                                                                                                                                                I know fixing the root cause is the best solution, but I am just curious.

                                                                                                                                                                                                                                                                                • 135. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                                  elifas

                                                                                                                                                                                                                                                                                  I am experiencing a problem with a coil type relay(from IDEC Corp product number is  RR3PA-UDC24VRR3PA-UDC24V

                                                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                                                  It is in a hydraulic drill MD6290 by CAT in a mine down in southern Africa. I am thinking of replacing it with a solid state relay but I cant figure out which type of solid state relay will fit in perfectly with the usage of this coil relay (It is used as a propel relay.

                                                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                                                  I need your assistance and guidance in selecting a solid state relay that best fits the duties done by this coil relay.

                                                                                                                                                                                                                                                                                  • 136. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                                    kaygee

                                                                                                                                                                                                                                                                                    Hello.

                                                                                                                                                                                                                                                                                    pls what is the impact of mistakenly applying 24Vac@1A to SSR designed 3-35Vdc, input. is the  relay destroyed or not?

                                                                                                                                                                                                                                                                                    • 137. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                                      kcmak

                                                                                                                                                                                                                                                                                      Can I use a single phase SSR to switch a heater load supplied by line voltage (line voltage means the phase to phase voltage from a 3-phase system)? If not, what is the appropriate connection?

                                                                                                                                                                                                                                                                                      • 138. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                                        deodutt

                                                                                                                                                                                                                                                                                        Hi Pete,

                                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                                        I am planning to buy a mechanical flow switch (SPST, 10VA, normally open) type. Would I be required to buy a solid state relay alongwith this switch to control circuit?

                                                                                                                                                                                                                                                                                        Regards,

                                                                                                                                                                                                                                                                                        Deodutt

                                                                                                                                                                                                                                                                                        • 139. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                                          nedwilsher

                                                                                                                                                                                                                                                                                          I have a project and know virtually nowt about electronics. I want to build an electronic switch that behaves in a particular way. In classic cars it is typical to put an isolator toggle-switch (SPST) in the ignition circuit. The switch is hidden under the dashboard or seat. The trouble is most thieves know about them and simply look in the obvious places. So I want to take the idea one step further. I will 'hide' my toggle-switch but this will be conected to a further second hidden switch. The trouble is that if theives can find one switch they may find the second. So my second switch will be a micro push-switch well hidden, perhaps behind a door card, that I have to assert pressure on to throw the switch. My aim is to first push the push-switch when I throw the toggle-switch. Then my electronic switch will activate and remain on when I release the pressure. The electronic switch will remain in this state no matter whether I push the push-switch on/off. The electronic switch would deactivate when the toggle-switch is thrown off. If, however, I thow the toggle-switch on before I have pushed the push-switch the electronic switch will not avtivate, and no matter what I do with the push-switch. I would have to turn off the toggle-switch and start again.

                                                                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                                                          I have had a go at this drawing up with mechanical latching relays (see diagram below). Is there an easier way with solid state technology? Incidentally, relay C in the diagram is not part of the switch. That just shows how I would use it in practice (ie, a battery isolator relay).

                                                                                                                                                                                                                                                                                          The theory here is that to trigger relay C I have to have the DPST (push-switch) on (down) so that when I throw the SPST (toggle-switch) relay B latches and passes current to relay C. As relay B is latched the subsequent release of the push-switch has no effect. However, if I just throw the toggle-switch then relay A latches. This disengages the push-pull switch from relay B so the relay cannot be triggered even if I push the push-switch; and, therefore, no power can go to relay C.

                                                                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                                                          Thanks.

                                                                                                                                                                                                                                                                                          • 140. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                                            aadityagovil
                                                                                                                                                                                                                                                                                            . i am using the same solid state replay in a machine. Now, what  happening is , due to some problem the input wire, which switches off and on the SSR with a minor current, is not working properly, due to which the relay is not passing on the input current to the load output. Can you suggest me if there is any way i can bypass the relay and make it work.
                                                                                                                                                                                                                                                                                            Righgt now, I really don't need the input wire to state when and when not to switch the relay.

                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                            • 141. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                                              rickalexander

                                                                                                                                                                                                                                                                                              Pete

                                                                                                                                                                                                                                                                                              I'm looking for a solid state 30-40 amp relay to control 240v power to my home water heater.

                                                                                                                                                                                                                                                                                              I purchased two 1 pole 40 amp on Amazon for about  $6-8 each.   The input signal is 120 volt from a home automation system.

                                                                                                                                                                                                                                                                                              Both relays have failed. (the relays were mounted on heat sinks but the power connectors melted loose from the device. The screw connection for the wire was tight, when installed)

                                                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                                                              Can you recommend a solid state device that will hold up with the load (19 amp)?

                                                                                                                                                                                                                                                                                              My next option is an expensive mechanically held contactor.

                                                                                                                                                                                                                                                                                              Rick

                                                                                                                                                                                                                                                                                              • 142. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                                                peteroakes

                                                                                                                                                                                                                                                                                                Where the ones you purchased, no name Chinese brand or a well known brand like OMRON ?. oftem items available from EBAY or Amazon are not built to the standards required for the advertized raing and as you have seen, can fail prematurly

                                                                                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                                                                                Overheating of connectors is as you probably know, due to bad connections or inadequate wire thickness resulting in both cases to excess heat at the joints and close wireing, the heat will inturn increase resistance causing the problem to cascade

                                                                                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                                                                                A 40Amp relay should easily take 20Amps so if your connectors failed I would suspect a fake part possibly shown able to handle more current that it is built for or cheaply made part

                                                                                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                                                                                Can you link in the exact part from Amazon you used ?, and provide pictures of your install so we can better help

                                                                                                                                                                                                                                                                                                 

                                                                                                                                                                                                                                                                                                Thanks

                                                                                                                                                                                                                                                                                                Peter

                                                                                                                                                                                                                                                                                                • 143. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                                                  shabaz

                                                                                                                                                                                                                                                                                                  Purchasing a relay from Amazon is like buying an airplane from a restaurant menu : )

                                                                                                                                                                                                                                                                                                  Amazon is not geared up to provide any deep search on technical parameters for relays or other electronic components, and I wouldn't trust the description field where the seller on Amazon could have meant 14Amps and mistakely typed 40A : ) (I'm being [overly] kind to the seller ; )

                                                                                                                                                                                                                                                                                                  • 144. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                                                    mcb1

                                                                                                                                                                                                                                                                                                    Not always.

                                                                                                                                                                                                                                                                                                    I once added a reputable contactor to a spa pool controller, and it also suffered from burning at the wire connection.

                                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                                    I'm not sure if it was poor contact from the lug, or the contactor chattering that resulted in the heat being dissipated at the wire end of the contact.

                                                                                                                                                                                                                                                                                                    Since heat always tries to migrate towards the colder area, its likely the wire will become a heat sink, and will add to any heating the resistance of the joint produces.

                                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                                    In many cases the screw is not covering the connector and with some connections the surface is not flat, so there could be some resistance present.

                                                                                                                                                                                                                                                                                                    Every time the element turns on the inrush current will be higher than the steady state 19 Amps.

                                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                                    The answer may be to use a solid state relay, where the ON is at zero, so the inrush current is reduced.

                                                                                                                                                                                                                                                                                                    The other option is to use a zero cross Optocoupler to drive the relay.

                                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                                    Mark

                                                                                                                                                                                                                                                                                                    • 145. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                                                      mcb1

                                                                                                                                                                                                                                                                                                      Can you link to the product.

                                                                                                                                                                                                                                                                                                      It might be that it does have a 40 amp rating but not for what you want.

                                                                                                                                                                                                                                                                                                       

                                                                                                                                                                                                                                                                                                      19 x 240 = 4560 Watts which is one heck of a water heater.

                                                                                                                                                                                                                                                                                                      If you are running two elements, you may want to consider splitting the control.

                                                                                                                                                                                                                                                                                                       

                                                                                                                                                                                                                                                                                                      Mark

                                                                                                                                                                                                                                                                                                      • 146. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                                                        Bryggeren

                                                                                                                                                                                                                                                                                                        Pete,

                                                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                                                        Thanks for answering all thees questions..

                                                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                                                        I've plan to use the D4850 for controlling the Camco 02963 element http://www.amazon.com/Camco-02963-Screw-In-Ripple-Element/dp/B000BPG4LI

                                                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                                                        I have 3 kettles each fitted with 3 elements connected to a 3 phase 400V supply in a star-configuration with common zero, witch give each element 230 V.  9  heat elements each having it's own D4850.

                                                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                                                        I have an aluminum heat sink it's 100 cm long, 10 cm wide and the ribs are 3 cm high. Ther'e 10 ribs acros the 10 cm. It's black , not painted, but i don't know the english word for that kind og coloring alkuminum. The SSR's will be screwed to the heat sink with heat conducting paste between the SSR and the heat sink. A fan ensure the circulation of air over the heat sink.The room temp is around 22 - 24 degree C.

                                                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                                                        Can you tell me if this particular heat sink with the fan provide enough cooling? I don't have any data on the heat sink.

                                                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                                                        My reason for asking, is that i just melted 3 FOTEK 40A/380V. The heat sink, at the relay positions, was never more than just above lukewarm. The mounting is the same as described above.

                                                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                                                        One more question. Which Crydom SSR should i use if i want to control the power with PWM, to the same heating elements as above?

                                                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                                                        Thank you.

                                                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                                                        Best regards

                                                                                                                                                                                                                                                                                                         

                                                                                                                                                                                                                                                                                                        Lars

                                                                                                                                                                                                                                                                                                        • 147. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                                                          peteroakes

                                                                                                                                                                                                                                                                                                          You can not really PWM these, atleast not at any significant frequency as once there on they will stay that way until the mains crosses zero volts again (Function of a Triac and SCR)

                                                                                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                                                                          On off control of course is doable but I would recomend to be in excess of one second or more pulses (Could still be called PWM of course). a 3 term controller is more of what I would expect for this (PID Control)

                                                                                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                                                                          anyway,  the rating of your cable needs to be atleast 8AWG as any thinner is not recomended for transmission line which is what you have when carrying 25Amps, you should also have appropriatly rated crimped connectors to go to the relay power side and the screwes torqued down correctly , see here: http://www.powerstream.com/Wire_Size.htm

                                                                                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                                                                          As your proposed relays are 50A rated and your switching 23A, your heatsink solution should be ok

                                                                                                                                                                                                                                                                                                          • 148. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                                                            panandy2

                                                                                                                                                                                                                                                                                                            Hi Pete,

                                                                                                                                                                                                                                                                                                            How does one go about finding the 12T parameters of a SSR, with a 14VDC control voltage and an actual load of 230VAC, 3amps, 0.6hp motor, I wish to protect the SSR with a circuit breaker.

                                                                                                                                                                                                                                                                                                            The specs for the SSR are Control 3-32VDC and Load 75-480VAC, rated 10amps.

                                                                                                                                                                                                                                                                                                            The whole show is been driven by a PLC.

                                                                                                                                                                                                                                                                                                            Thank you.

                                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                                            Kind Regards,

                                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                                            Andy Munro.

                                                                                                                                                                                                                                                                                                            • 149. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                                                              steveraleigh

                                                                                                                                                                                                                                                                                                              Greetings,

                                                                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                                                                              I need someone to tell me which relay to zero in on. One manufacturer to stick with for my simple application.There are too many choices! Too much research!

                                                                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                                                                              Here's the background- I am a high end residential electrician. I am used to using mechanical contactors. The problem is that they are too noisey. What I control is pretty simple. Here's the range...

                                                                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                                                                              1) Control 120V / Single phase.

                                                                                                                                                                                                                                                                                                              2) Amperage- 20 Amp 95%, 30 Amp 5%.

                                                                                                                                                                                                                                                                                                              3) Single Pole and 2 Pole.

                                                                                                                                                                                                                                                                                                              4) Mounted in metal J-box with cover.

                                                                                                                                                                                                                                                                                                              5) Usually 12x12x4.

                                                                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                                                                              Thanks-

                                                                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                                                                              Steve / Desert Home Electric

                                                                                                                                                                                                                                                                                                              • 150. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                                                                peteroakes

                                                                                                                                                                                                                                                                                                                What is your control signal to energise / turn on the relays / contactors. SSR's are often limited to 3-30V on their inputs

                                                                                                                                                                                                                                                                                                                • 151. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                                                                  PeteB

                                                                                                                                                                                                                                                                                                                  Hi Steve.   

                                                                                                                                                                                                                                                                                                                  The use of SSR's for quiet operation is a great benefit.   However, there are a number of things that need to be considered and addressed to use an SSR properly where you end up with a successful and very reliable system.   Most important is how to address and handle the internal heat that an SSR generates when passing load current.     As a start, I could suggest the Crydom A2425 or A2450, (90 - 280 Vac control, 24-280 Vac load at 25 or 50 amp), but the use of the derating curves on the datasheet is of prime importance to select the proper heatsinking for the actual load currents and the expected highest ambient temperatures surrounding the SSR / Heatsink.  To be sure you've got all of the best information, I'd be glad to discuss and assist you with this off-line if you'd send me your contact information to:   Pete.Bamburak@cstsensors.com

                                                                                                                                                                                                                                                                                                                   

                                                                                                                                                                                                                                                                                                                  Regards,

                                                                                                                                                                                                                                                                                                                  Pete B. 

                                                                                                                                                                                                                                                                                                                  • 152. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                                                                    PeteB

                                                                                                                                                                                                                                                                                                                    Hi Andy.

                                                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                                                    The information / datasheets for all Crydom  SSR's include a specific line item in the "Output Specification" section titled " Maximum 1/2 cycle Isqt for Fusing".   For  the Crydom D2410, that value at 60 Hz is 60 A sq-sec.

                                                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                                                    Regards,

                                                                                                                                                                                                                                                                                                                    Pete B.

                                                                                                                                                                                                                                                                                                                    • 153. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                                                                      timmy2tones

                                                                                                                                                                                                                                                                                                                      I've seen a few AC input SSR's but they all start at 80VAC.  Are there any lower voltage  range SSR's?   40VAC would be my application.

                                                                                                                                                                                                                                                                                                                       

                                                                                                                                                                                                                                                                                                                      Tim

                                                                                                                                                                                                                                                                                                                      • 154. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                                                                        peteroakes

                                                                                                                                                                                                                                                                                                                        you may need to simply rectify your control, and use a limiting resistor to the 3-30V ones

                                                                                                                                                                                                                                                                                                                        • 155. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                                                                          PeteB

                                                                                                                                                                                                                                                                                                                          Hi Tim,

                                                                                                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                                                                                          Beyond offering many types of 90 - 280 Vac input SSR's, (along with options for 18 - 36 Vac input), Crydom's "CW" series also offers a "U" (Universal) input that covers AC Control signals of 20 to 280 Vac.   That would handle your 40 Vac input easily.   FYI, the "U" input also accepts 20 to 48 Vdc too.

                                                                                                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                                                                                          http://www.crydom.com/en/products/catalog/c_w24.pdf

                                                                                                                                                                                                                                                                                                                          http://www.crydom.com/en/products/catalog/c_w48.pdf

                                                                                                                                                                                                                                                                                                                           

                                                                                                                                                                                                                                                                                                                          Pete B.

                                                                                                                                                                                                                                                                                                                          • 156. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                                                                            franktank

                                                                                                                                                                                                                                                                                                                            Hi Pete

                                                                                                                                                                                                                                                                                                                            This site is awesome.

                                                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                                                            I just discovered SSRs, had previously tried using transistors as such with no success. They clearly were not the answer I was looking for.

                                                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                                                            The situation in mind is using an SSR to take the load off a set of points to power an ignition coil on an old motorcycle.

                                                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                                                            I assume I  need a snubberless model, good for a couple amps at about 14vdc, or better obviously. Waterproof would be necessary.

                                                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                                                            Could you suggest a part number and basic hookup instructions for the circuit? I imagine I could figure it out, but then again I thought that before. Lol

                                                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                                                            The signal from the points is a switched ground.

                                                                                                                                                                                                                                                                                                                            And condensers, of course.

                                                                                                                                                                                                                                                                                                                             

                                                                                                                                                                                                                                                                                                                            Thank you

                                                                                                                                                                                                                                                                                                                            Frank

                                                                                                                                                                                                                                                                                                                            • 157. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                                                                              PeteB

                                                                                                                                                                                                                                                                                                                              Hi Frank.

                                                                                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                                                                                              Glad you like the Element 14 site!  

                                                                                                                                                                                                                                                                                                                              Regarding a Solid State Relay as part of an ignition system, (as you describe to take the load off the points and interface with an ignition coil), you'd first need to consider use of a DC output SSR...  on the order of a Crydom DC60D10, (60 Vdc switch, 10 amp max, 4-32 Vdc control).   However, you'll likely encounter a couple of issues that will cause you some problems in using the SSR for this purpose. 

                                                                                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                                                                                              First, there are various delay times in the on and off operation of the solid state relay due to the circuit passing the trigger signals across the isolation between the input and the output. These delays could come into play at high RPM's 

                                                                                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                                                                                              The second would be in protecting the output of the DC SSR against back EMF spikes, high voltage noise, etc., that could easily damage the SSR power section.  That is typically done with a reverse biased diode across the load.. here it would be across the primary of the ignition coil. But when doing that, the diode will affect the discharge characteristics of the coil which may affect your ignition spark.   (check out the Wikipedia article on "Flyback Diode" ...and the effects on "Delayed Drop out" under the "Design" paragraph).

                                                                                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                                                                                              https://en.wikipedia.org/wiki/Flyback_diode


                                                                                                                                                                                                                                                                                                                              Third, even if you are able to overcome the 2 concerns I note, the cost of the SSR alone would likely be greater than the cost of a small capacitive discharge ignition module specifically designed for motor cycles.

                                                                                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                                                                                              From a "techie" standpoint, your project sounds interesting, and I hate to dissuade you from experimenting with SSR's.       But from a practical view, checking out an add-on CDI system would likely be your best route.

                                                                                                                                                                                                                                                                                                                               

                                                                                                                                                                                                                                                                                                                              Pete B.

                                                                                                                                                                                                                                                                                                                              • 158. Re: Have a question about solid state relays and their applications? Ask me!
                                                                                                                                                                                                                                                                                                                                missprinceyy

                                                                                                                                                                                                                                                                                                                                Hi,

                                                                                                                                                                                                                                                                                                                                I'm checking the Crydom HDC Series SSR. I am confused about the meaning of "operating voltage". They have several ranges include 7-48V, 7-72V, 7-150V. What is this voltage indicate?

                                                                                                                                                                                                                                                                                                                                Thanks.