Relay Application Surge Suppression Function

1. What is a surge
A surge is a peak that momentarily exceeds a stable value. It can be divided into surge voltage and surge current. What we commonly encounter is surge voltage, which is a temporary overvoltage that exceeds the normal operating voltage. Some surges are generated internally, while others come from external sources. Surge current is more commonly referred to as overcurrent, and protective measures such as short-circuit protection, overload protection, and using thermal relays are generally employed to prevent it.
2. How relay surges are generated
After energy is injected into a relay coil, the moment the switch opens, a large surge voltage is generated. This is an internally generated surge voltage. Although it appears as a violent pulse lasting only a few millionths of a second, it can cause significant interference to external circuits, especially electronic circuits, and can even instantly damage them. When multiple relays are used simultaneously, the surge intensifies and they can interfere with each other.
3. The function of relay surge suppression
When a relay operates in an electrical circuit, it is subjected to surge voltages and currents from both internal and external sources. The relay surge suppression function only suppresses the surges generated internally to eliminate their impact on external circuits. External surges are unpredictable and are a consideration for engineers when designing the overall circuit. External surges can also cause significant damage to the relay, which requires engineers to take preventive measures in advance.
4. Improper use of relay surge suppression function
Improper or excessive suppression may result in prolonged relay release time, slower contact separation, and increased contact bounce. These issues can cause arcing at the contacts when the load is turned off, thereby reducing the relay's lifespan. Therefore, simply adding this function is not necessarily beneficial; it should be determined according to one’s specific needs.