GB1053654A - - Google Patents

Abstract

1,053,654. Automatic circuit-breakers. FEDERAL PACIFIC ELECTRIC CO. May 21, 1963 [May 21, 1962], No. 20252/63. Heading H2B. A multipole circuit breaker has a bimetal 24 in each pole to operate a common trip bar 70 in response to an overload and also has a magnetic tripping device, said device comprising a channel-shaped core 86 behind each bimetal 24 and a double-ended armature 98 mounted between the bimetal 24 and the trip bar 70 for rocking movement from its normal position where end 98a of the armature has a magnetic back-pull toward a pole face 94a at low current levels and where end 98b moves towards the core 86 at higher current levels such that end 101 of the armature operates the tip bar 70 to free a latch 61, which in turn rotates and releases cradle 46 with consequent collapsing of the toggle mechanism 38 and opening of the breaker contacts 16, 18. Adjusting screw 104 sets the gap between armature end 98a and polepiece 94a, and a spring 102 biases the armature about its pivot 99 against the core 86. The tip bar 70 has secured to it the latching part 77, which is bimetallic to provide ambient temperature compensation, and bar 70 carries an adjustment screw 84 which is engaged by bimetal 24 when it deflects to operate the trip bar. An insulating barrier 108 separates core 86 from the current-carrying flexible braid 22. The operating mechanism, the releasable cradle 46, the latch 61 and the trip bar 70 are carried by a common metal frame 44, as claimed in Specification 1,053,655.