Thermal protector Thermal switch is a kind of temperature switch which uses bimetallic sheet as temperature sensing element. When the electrical appliance works normally, the bimetallic sheet is in the Free State, and the contact is in the closed/open state, when the temperature rises to the operating temperature value, the bimetallic element acts quickly due to internal stress caused by heating. Open/close the contact and cut off/connect the circuit, thus playing a role of thermal protection. When the temperature drops to the reset temperature, the contact automatically closes/disconnects and returns to the normal working state. Widely used in household electrical appliances and electrical equipment, such as washing machine motor, air conditioning fan motor, transformer, ballast, electric heating appliances, etc.