GB860784A - Improvements in and relating to automatic electric circuit breakers - Google Patents

Abstract

860,784. Automatic circuit-breakers; switch cases. HARGREAVES, B. Jan. 30, 1958 [Nov. 6, 1956], No. 33923/56. Class 38 (5). The moving contact 25 is normally held engaged with fixed contacts 23, 24 by interengaging parts 17. 18 which may be released on overload to allow the contacts to open, the part 17 being carried by a cover 11 which is movable manually to open the contacts without tripping. The contact 25 has an extension 26 secured by a bolt 27 to a bimetal strip 15 which is pivoted at 12 and biased clockwise, Figs. 1 and 3, by a spring 35 secured to the cover at one end. The bolt 27 carries a chamfered nut 18 which co-operates with a recess in a latch arm 17 of a latch 16 pivoted at 16a on the cover. The latch has an armature 20 which in the closed position, Fig. 1, is near a magnet 21 formed by a strap bent round conductor 22, so that with a short circuit, the armature is attracted to disengage parts 17, 18. With a prolonged overload, bimetal 15 deflects to the left, Fig. 4, to disengage these parts. In either event, the spring 35 separates the contacts and the parts take up the Fig. 3 position in which an arm 15a carrying the bimetal abuts a screw 31 on the base 10. The parts 17, 18 are reset by moving the cover outwards to the Fig. 5 position to an extent allowed by the movement of a slot 41 therein past the screw 31. The contacts are reclosed by returning the cover to the Fig. 1 position where the cover is held by a spring 32 on the base engaging a shoulder 34 on the cover. The contacts may be manually opened by moving the cover to the Fig. 5 position. The air gap between parts 20, 21 may be adjusted and the nut 18 may be adjusted along bolt 27. A number of breakers may be clipped side-byside on to a common support-bar 1, Figs. 6, 7 (not shown). The latch 16 carries the word " TRIP " which becomes visible through a window 39 in the Fig. 3 position, and the base carries the word " ON " which is visible in the slot 41 in the positions of Figs. 1 and 3, but is invisible in the Fig. 5 position. Specification 860,785 is referred to.