THERMALLY SENSITIVE CONTROLS

摘要

A thermally sensitive, overheat protection control for a thick film electric heater comprises a bimetallic actuator (68) arranged for making good thermal contact with the heater, and a movable electrical contact (78) for engagement with a contact provided on the heater. The movable contact (78) is operatively coupled to the bimetallic actuator (68) such that in use upon operation of the actuator, it moves out of engagement with the heater contact to interrupt the electrical supply to the heater. The bimetallic actuator (68) and the movable contact are mounted on a common generally U-shaped leaf spring (66) which acts in use resiliently to bias the actuator (68) into thermal contact with the heater and the movable contact (78) into electrical contact therewith. The control also comprises a creep action bimetallic actuator (110) mounting a contact at one end thereof, the actuator acting as a thermostatic control for the heater.