Main parts

1) Shell  2) Iron bracket  3) bimetal disc

4) movable contact  5) Base  6) stationary silver contact

Construction

The movable contact are welded to the bimetal sheet and then wel-

ded to the iron bracket. The stationary silver contact and base are 

molded into a whole, and then the base is riveted with the iron bra-

cket. The current first passes through the movable contact on the 

bimetal disc from the iron bracket, and then passes through the sta-

tionary silver contact to form a loop.

Function

Under normal conditions, the moving contact is in close contact 

with the stationary silver contact under the pre-pressure of the bi-

metal disc; When the rated operating temperature is reached, the 

bimetal disc is deformed by heat and snap rapidly, cut off the circuit. 

After that, the device begins to cool down. When it reaches the de-

fined reset temperature, the bimetal disc and the spring disc snaps 

back into its start position,  the contacts will close again,  and the 

device starts working again.