1 2 3 4 520 Replies Latest reply on Jun 17, 2020 2:42 AM by devesh_rai Go to original post
      • 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

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              • 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
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