Q. What is the work of static relay?

Answer

By comparing or measuring electrical quantities the static relay triggers an action. Comparators level detectors zero-crossing detectors and similar static electronic circuits are used to make the comparison and provide the output signal necessary to trip the circuit breaker. Unlike an electromagnetic relay which has a moving armature a static relay has no such components. While typical electromagnetic relays don't have any moving parts developments in semiconductor technology have allowed static relays to replace them.