GB1031971A - Improvements in or relating to electric circuit breakers - Google Patents

Abstract

1,031,971. Automatic circuit breakers. D SQUARE CO. March 13, 1964, No. 10610/64. Heading H2B. The circuit breaker described in Specification 893,282 is rearranged for higher voltage, lower current rating so as to incorporate within a casing having the same overall dimensions an improved arc-chute 74, 75 and an electromagnetic tripping device of higher ampere turns. The tripping device comprises a core 54 (Fig. 12, not shown) upon which is pivoted an armature 44 carrying a latch plate 52. A bimetal 70 passes through the core 54 and acts upon a part 45 of the armature. About one arm of core 54 is wound a coil 66 connected between the line terminal 64 and the secured end of the bimetal 70. For maximum sensitivity the coil 66 can be of nickel chromium alloy acting as a heater for the bimetal. For reduced sensitivity coil 66 is reduced in turns until in the limit (Fig. 9, not shown) it comprises a simple strap 80 which together with bimetal 70 forms a single turn. Further reduction may be achieved by bending a tongue 82 on the core 54 which supports it in the housing thus increasing the air gap between the armature 44 and core 54. Conjoint actuating links and tripping bar can be inserted at 35, 50 respectively for multiple use.