The NEC SCHOTT SEFUSE® SM type is a thermal cutoff designed to protect electrical home appliances and industrial electrical equipment from catching fire. It contains a fusible alloy inside an insulated case which interrupts the electrical circuit by melting when ambient temperatures reaches abnormal levels.
The device is integrated into the electrical circuit of the appliance. Two leads are connected in the device by a fusible alloy, which is coated with a special flux. Under normal conditions, the current flows directly from one lead to the other through the fusible alloy. In case the ambient temperature should reach a critical point, the fusible alloy will melt and then condense into a drop around the end of each lead caused by surface tension and the special coating. As a result, the electric current is interrupted immediately.