What occurs when a melting alloy overload in a magnetic motor starter actuates?

When a melting alloy overload in a magnetic motor starter actuates, it specifically helps to ensure the safety of the motor circuit by opening the control circuit. This action is a critical protective measure that prevents the motor from operating under potentially harmful conditions, such as overload or overcurrent situations. By opening the control circuit, it effectively cuts power to the coil of the contactor, leading to the opening of the power contacts and thereby stopping the flow of electricity to the motor.

This mechanism works to safeguard the motor and other components from damage that could be caused by excessive current draw. The melting alloy responds to heat generated by the overload, which serves as a reliable method for detecting abnormal conditions and initiating the protective response.

In contrast, while opening the power circuit contacts or disconnecting the power supply to the starter might seem like valid outcomes of an overload condition, they are not the direct action of the melting alloy itself. Additionally, requiring an immediate reset might apply once the situation is remedied, but it isn't the initial action taken when the overload actuates.