What type of thermal overload device uses melting alloy for operation?

A thermal overload device that uses a melting alloy for operation is the solder pot. This device functions by incorporating an alloy that has a specific melting point, which serves as a safety mechanism. When the temperature exceeds this limit, the alloy melts, effectively opening the circuit and disconnecting the electrical supply. This action prevents overheating and potential damage to the electrical system or connected devices.

Other types of thermal overload devices operate on different principles. For instance, a bimetallic strip relies on the different expansion rates of two metals bonded together to bend and open a circuit, while a magnetic relay uses the magnetic field generated by an electrical current to activate a switch. A thermal fuse, on the other hand, is designed to cut off electrical flow by permanently breaking the circuit once the temperature threshold is reached, but it does not use a melting alloy in its operation. The solder pot's reliance on a specific melting alloy underpins its effectiveness as a thermal overload protection device.