Correct Answer - Option 3 : bimetallic-strip
Miniature circuit breaker (MCB)
1. A miniature circuit breaker (MCB) automatically switches off the power supply during overload and faults.
2. This function of automatic switching is accomplished by a bimetallic strip.
3. Whenever continuous overcurrent flows through MCB, the bimetallic strip is heated and deflects by bending.
4. This deflection of the bimetallic strip releases a mechanical latch.
5. As this mechanical latch is attached to the operating mechanism, it causes to open the miniature circuit breaker contacts, and the MCB turns off thereby stopping the current to flow in the circuit.
