A thermal fuse or thermal cut-off is a device that is used to prevent electrical appliances from overheating. It is a small device that plays an important role in preventing fires. A thermal fuse is used where safety is the primary concern as it keeps appliances from overheating. It is designed to detect abnormal rises in temperature and break circuits. A thermal fuse completely burns if the machine gets beyond its safety level.
Unlike an electrical fuse, a thermal fuse is melted by excessive heat instead of being shorted out by excessive current. A thermal fuse uses a one-time fusible link. Unlike a thermal switch, which may automatically reset itself when the temperature drops, the thermal fuse is more like an electrical fuse: a single-use device that cannot be reset and must be replaced when it fails/burns out. A thermal fuse is used when the overheating is a result of a rare occurrence, such as failure requiring repair (which would also replace the fuse) or replacement at the end of service life.
The thermal fuse becomes operational when the thermal element inside the fuse melts. Furthermore, if the thermal element inside the thermal fuse does not reach the operating temperature, the thermal fuse does not operate even if the ambient temperature rises to the operating temperature. A thermal fuse uses a fusible link, which consist of two pieces of metal that are attached together by a substance designed to melt at a particular temperature. Under normal circumstances, current runs between two plates, running an appliance. A thermal fuse only works one time. If it is triggered during a high-exhaust temperature event, the fuse must be replaced.