HEAT-FINANCIAL ELECTRICAL SCALE

摘要

A thermally-responsive electrical switch for use in domestic electrical appliances for switching off the electrical supply to the appliance in an over temperature situation is configured to be manufactured as an auto-reset switch, as a manual reset switch, or as a PTCR switch without significant manufacturing changes. The switch body (20) is moulded plastics and incorporates first and second terminal parts (1, 2), one of which provides a cantilever mounting for a switching element (4) which moves to effect switching operations between its free end and the other terminal part. A bimetallic switch-actuating element (7) is mounted on the switching element (4) so as by its temperature-responsive movements to effect switch-operating movement of the switching element. The switch body (20) is configured to be capable of accepting a PTCR element (11), which is retained by a conductor (12) such that the PTCR element (11) is placed in a current conducting path through the switch when the switch contacts are opened, the heat developed in the PTCR element (11) then holding the condition of the switch whilst substantially reducing the through current to the switch load. By omission of the PTCR element, an auto-reset switch is obtained, and by selection of the characteristics of the bimetallic element and/or arranging the switching element to be bistable, a manual reset version of the switch can be obtained.