GB1429845A - Thermally-responsive actuator - Google Patents

Abstract

1429845 Thermal switches; automatic circuit - breakers ALLMANNA SVENSKA ELEKTRISKA AB 6 June 1973 [7 June 1972] 27014/73 Heading H1N [Also in Division G1] A thermally responsive actuator consists of a bimetallic bowed disc I peripherally supported on a metallic base-plate 5, against the force of a leaf-spring 4, by a screw and nut 2, 3 used for adjustment of the operating temperature at which the disc snaps over to being bowed in the opposite direction, the snap movement being aided by the spring 4. In Fig. 1 the screw 2 acts on a release member 6 for moving a contact member of a switching device whilst in Fig. 3 the release member 6 is replaced by a lever 7 for amplification of the disc movement or for constituting a movable contact member of a switch. A thermally responsive switching device to Fig. 3 arrangement can also incorporate magnetic overcurrent release means comprising a magnetic core 8 surrounding the base-plate 5 acting as a current conductor with the lever 7 acting as an armature. The actuator is described as being manually reset and ambient temperature compensation can be provided by making the leaf-spring 4 of bimetallic material or by reinforcing it with a separate bimetallic spring. The bimetallic member 1 may be a plate of any shape and a helical spring may be used instead of the leaf spring.