Main parts

1) Ceramic cover plate  2) stationary silver contact  3) shaft pin 

4) bimetal disc   5) spring disc  6) movable contact  7) housing

Construction

Stationary silver contact and ceramic covers are riveted together; The movable contact, bimetal disc and spring disc are riveted together by shaft pins. The movable contact is in close contact with the stationary silver contact under the pre-pressure of the spring disc; The current passes through the stationary silver contact and the movable contact to form a loop.

Function

When the circuit works normally, the movable contact and the stationary silver contact are in a closed state. When the rated operating temperature is reached, the bimetal disc is deformed by heat, and the spring disc is pushed downward through the riveting shaft pin, so that the movable and stationary silver contact are abruptly opened. After the circuit is disconnected, the ambient temperature begins to fall. When it reaches the defined reset temperature, the bimetal disc and the spring disc snaps back into its start position, the contacts will close again, and the circuit returns to the normal working state.