What are the effective protection measures for power relays in dealing with surge current?
Publish Time: 2025-01-22
Power relays can take a variety of effective protection measures in dealing with surge current to ensure their stable operation and extend their service life.
Configure air switches:
Choose air switches with overcurrent protection function. When surge current or overcurrent is detected, the air switch can automatically trip and quickly cut off the power supply, thereby protecting the power relay from damage.
Add fast fuses:
Connect fast fuses in series in the control circuit of the power relay. When the current exceeds the set value, the fuse will quickly melt and cut off the circuit to prevent surge current from damaging the relay.
Use varistors:
Connect varistors in parallel at the input or output of the power relay. A varistor is a component whose resistance value changes with voltage. When the voltage exceeds a certain value, its resistance value decreases sharply, thereby absorbing and dissipating surge voltage and current.
Choose a suitable varistor according to the system voltage. For example, in a 220V system, a 500V-600V varistor can be selected; in a 380V system, an 800V-900V varistor can be selected.
Connect an RC absorption circuit in parallel:
Connect an RC (resistance-capacitance) absorption circuit in parallel at the output end of the power relay. This circuit can absorb and disperse overvoltage, thereby protecting the internal components of the relay from damage by surge current.
Choose a relay with output protection:
When purchasing a power relay, you can choose a relay product with a built-in varistor absorption circuit and an RC buffer. These built-in components can effectively absorb surge current and improve the dv/dt tolerance of the relay.
Use TVS diodes:
TVS (transient voltage suppression) diodes are components with high-performance surge suppression capabilities. Connecting them to the input or output of a power relay can absorb and dissipate surge voltages and protect the relay from damage.
Designing a surge bypass protection circuit:
By designing a surge bypass protection circuit in the circuit, the surge current can be bypassed when it is generated, thereby avoiding impact on the power relay. This circuit usually includes components such as capacitors and inductors, which can absorb and disperse surge energy.
In summary, power relays can take a variety of effective protection measures to deal with surge currents. In practical applications, appropriate protection measures should be selected according to specific scenarios and needs to ensure the stable operation of the power relay and extend its service life. At the same time, attention should also be paid to regular inspection and maintenance of the protection circuit to ensure that it is always in good condition.
