GB739620A - Improvements in or relating to automatic electric circuit breakers - Google Patents

Abstract

739,620. Automatic circuit breakers; contact members for switches. FEDERAL ELECTRIC PRODUCTS CO. Jan. 22, 1954, No. 2041/54. Class 38 (5). The member 24 carrying the movable contact 22 of a circuit breaker is mounted on a movable pivot at which is provided spring means or which is (Figs. 1 and 2) itself of spring wire 52, an actuator 28 being pivoted to member 24 and connected by a link 30 to a handle 26. A bimetal latch 40 engaging the actuator 28 and an electromagnetic device 42 which attracts the latch 40 form overload releases, the switch being then opened by a spring 46. The pivot 52 is flexed and moved slightly downwards by the bodily downward movement of member 24 on closing the switch, metal sleeves 54 on the ends of the pivot bearing and moving downwards in recesses 56, 58 in casing parts 10, 12 respectively. This tensioning of the spring urges the member 24 upwards, thus ensuring sufficient pressure between contacts 20, 22. While closing the switch, and when the handle is in the intermediate vertical position, contacts 20, 22 just engage, and as the handle is moved further clockwise (Fig. 1) the member 24 is also moved slightly laterally on pivot 52 to provide a " wiping " action between contacts 20, 22. In other embodiments (Figs. 7-11 and 20-26, not shown) the pivot is in the form of a coiled spring and strip of coiled spring metal respectively. In yet another embodiment (Fig. 14) the pivot is in the form of a tapered screw 72 carried in resilient bearings 96, 98, the tapered part 74 engaging part 60B of the movable contact member and constituting a calibration device, since by turning the screw, the amount of overlap between the bimetal member and the actuator can be varied. This can be achieved in the first three embodiments referred to by inserting a tool into a notch 70 in the member 24 and bending the latter slightly. The bearings 96, 98 are free to rotate or move laterally, thus providing for contact pressure and wiping action as before. In another embodiment (Fig. 28), the pivot is also in the form of a tapered pin mounted for vertical and lateral movement in elongated recesses 122, 124 in casing parts 10D, 12D, a spring member 126 (Fig. 36) with arms 132, 134 providing for the contact pressure.