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    Power Relays Quiz

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    This is a 25-question quiz focusing on information regarding electromechanical relays, electrical contacts, PCB power relays, and other technical information pertinent to relays.

     

    1) The physical separation between an electromechanical power relay's coil and contacts provides the appropriate level of __________ between the input and output.





     

    2) The typical switching time of an electromechanical power relay is ________.





     

    3) True or False: One of the benefits of a DC power relay is that it enables the electrical control of AC loads from a DC power source.


     

    4) True or False: Relay contact ratings are usually indicated for inductive and capacitive loads.


     

    5) ____________ contacts are divided into two parts to double the contact's make points, which provides some amount of independent dual contacting to increase the reliability of the relay contact and reduce contact bounce.





     

    6) True or False: A flux protection relay is housed in a corrosion-resistant, sealed case using metal or glass purged with inert gas (N2) to protect from corrosive gas penetration.


     

    7) What type of contacts are illustrated in the diagram on the right?





     

    8) When two or more relays are mounted closely together on a PCB, relay characteristics may be changed by interference from the magnetic fields generated by the individual relays. This condition is called:





     

    9) True or False: When the relay temperature changes, the springiness of the relay contact spring, the amount of friction, and the coil resistance all change. Of these, the amount of friction has the largest impact on the operating time.


     

    10) True or False: The operating time of the relay is determined by the coil time constant, delay time due to the moment of inertia, and the contact switching time.


     

     

    11) Silver migration occurs when certain humidity and oxidation-reduction conditions exist and a DC voltage is applied to silver electrodes for an extended period of time. This phenomenon causes the insulation to deteriorate and occasionally causes ________ problems.





     

    12) When mounting more than two G4A PCB Power Relays side by side, what is the recommended horizontal and vertical gap between the relays in order to ensure good heat dissipation?





     

     

    13) You have inspected a control panel and found that the contacts will not release. From the list below, which of the following is NOT a likely cause of the failure?





     

    14) If there is a film on the surface of a contact that is touching another contact, the film electrically breaks down and the contact resistance drops rapidly when the contact voltage exceeds a certain value. This condition is called:





     

    15) An electromechanical relay generates electromagnetic force when the input voltage is applied to the coil. The electromagnetic force moves the _________, which switches the contacts in synchronization.





     

    16) When a relay is being energized, the inductance of a relay winding is unstable and varies considerably. Why does this occur?





     

    17) The power consumption of a high sensitivity G2RL PCB power relay is approximately __________.





     

    18) True or False: Form C contacts combine Form A and Form B contacts in a single relay. When a voltage is applied to the coil, the Form C contact moves away from the Form B contact and mates with the Form A contact for single-side stable relays.


     

    19) True or False: If a relay is to be used for a microload, the reliability will depend on the contact material and contact method. Twin contacts are less reliable than single contacts because of the parallel redundancy they provide.


     

    20) ____________________ is the maximum abnormal voltage that the relay can withstand when the voltage surges momentarily due to lightning or switching an inductive load.





     

    21) What is the dielectric strength of a high durability G6DN PCB Power relay between the coil and the contacts?





     

    22) ____________ expresses a rough guide to the switchable limits of electronic circuits and other very small loads.





     

    23) What is the rated carry current of a high-capacity G2RL PCB Power Relay?




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    24) True or False: Nitric acid contact corrosion occurs when arcing due to load switching bonds nitrogen and oxygen in the atmosphere together to form HNO3, which corrodes metallic materials.


     

    25) True or False: It is not advised to solder relay lead wires to tab terminals because this can cause the relay structure to change or contact failure to occur due to flux penetration.


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