Bimetal thermal relays

Temperature protection relays

Bimetallic thermal relays

Thermal bimetallic relays are the simplest type of surge protection relay. Their construction consists of a heater that is connected in series to the motor and to the bimetallic strip. Bimetallic tape, as its name suggests, is made of two different metals bonded together. Since the two metals are different, their thermal expansion occurs at different rates. The heat from the heater is not enough to bend the bimetallic strip and trip the relay. In the event of a surge, the bimetallic strip heats up enough to bend and actuate the mechanism to stop the motor.

Thermal relay application

• The protection of electric motors from overvoltage
• Constant ambient temperature conditions
• Conditions with varying ambient temperature