What role does a melting alloy play in an overload relay?

A melting alloy in an overload relay plays a crucial role in protecting electric motors from damage due to excessive current flow. When an overload condition occurs, the current flowing through the circuit generates excessive heat. The melting alloy is designed to be sensitive to this heat; when the temperature rises beyond a certain threshold, the alloy will melt. This melting action interrupts the circuit, effectively shutting off the power to the motor and preventing potential overheating and damage.

This mechanism is essential for ensuring the longevity and safety of electric motors, as it acts as a fail-safe against prolonged overload conditions. By disconnecting the power supply when it detects dangerous levels of heat, the melting alloy protects the motor from failure and ensures safe operation.