What are surge countermeasures in coil relays?
The back electromotive force generated by the coil when it’s turned off may cause damage to the semiconductor or device malfunction. As a countermeasure, add a surge-absorbing circuit to both ends of the coil.
If a surge-absorbing circuit is added, the relay release time will be longer. Check the circuit before use.
- Driving DC coil relay: Diodes are typically attached to the relay coil.
- Driving AC coil relay: Varistors/CR elements are typically attached to the relay coil.
Examples of Surge Suppressors
For more information, see Safty Precautions for All Relays: 2-2-5 Preventing Surges When the Coil Is Turned OFF.
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