Why is the bimetal strip important in thermal-magnetic circuit breakers?

The importance of the bimetal strip in thermal-magnetic circuit breakers lies in its role in balancing thermal and magnetic protection. The bimetal strip is designed to respond to heat generated by overload conditions. When the current flowing through the circuit exceeds a certain threshold, the heat causes the bimetal strip to bend due to the different expansion rates of the metals that comprise it. This bending triggers the breaker to trip, disconnecting the circuit before any damage can occur, thereby providing essential thermal protection.

Simultaneously, the circuit breaker also includes magnetic protection, which is designed to react quickly to short circuits. The bimetal strip's function ensures that both protections work cohesively, allowing the breaker to trip under overload conditions without unnecessary delay or risk to the circuit. This integrated approach enhances the overall effectiveness of the circuit breaker in safeguarding electrical systems by ensuring both overload and short-circuit conditions are addressed appropriately.