What happens to the lever in a Thermal Overload Relay during an unbalanced current?

In a Thermal Overload Relay, the lever is designed to respond to variations in current flow, particularly during conditions of unbalanced current. When an unbalanced current occurs, one phase of the motor may draw more current than the others, resulting in increased heat generation. The thermal sensitivity of the relay causes the lever to react to this excess heat, leading to deflection.

As the current becomes unbalanced, the heat generated in the overload relay's thermal elements causes the lever to bend or move in response to the thermal expansion. This action amplifies the deflection of the lever, ultimately triggering the mechanism to trip the relay. This tripping action effectively interrupts the circuit and protects the motor from damage caused by overload conditions.

By amplifying the deflection, the thermal overload relay ensures that any significant deviations in current are sensed, allowing for prompt and efficient protection of the electrical system. This capability is crucial for maintaining the integrity and lifespan of motors and other connected equipment.