GB553105A - Improvements in or relating to electric circuit breakers - Google Patents

Abstract

553,105. Automatic circuit-breakers. JOHNSON & PHILLIPS, Ltd., and BLOOME, J. Nov. 18, 1941, No. 14822. [Class 38 (v)] The "making-current release" of a circuitbreaker comprises an armature which is movable under the influence of flux generated by an existing current-carrying part of the circuitbreaker or conductor leading thereto, to effect tripping. The movable bridging-contact 1 of an oil circuit-breaker is closed by counter-clockwise rotation of lever 11 about shaft 10 when a handle-actuated shaft 9 is rotated, and is opened by upward thrust of rod 12 by hand or an overload coil, so as to deflect a latch 13. An extension 23 thereon is also engageable by a lever 20 rotatable about pivot 21 by a rod 19 which is pivoted to part 18 of an armature structure 15 acting as making-current release. The structure comprises, in a three-phase switch with conductor studs 4 mounted in two rows, a pair of armatures 15 mounted in the gaps between the studs 4 of a row and carried on the same shaft 16, which is rotatable in bearings 17 on the tank-cover 8 against spring-action 24. The armature-extension 25 to which spring 24 is attached carries a further extension 28 over which a projection 27 on the closing-linkage engages in the fully-closed position of the breaker, thus immobilizing the making-current release. The spaces 14 in the tank-cover 8 extending between the apertures of adjacent studs of one row, which spaces are to break the induced-flux path and so reduce heating, are utilized as the interpolar spaces of the field system constituted by the cover 8, the armatures being acted upon by the leakage flux thereacross. In a modification, Fig. 3 (not shown), the field system comprises a yoke running the length of the row with a pair of transverse projections extending therefrom about each stud, a common bar armature co-operating with the ends of the projections and being rectilinearly movable or pivoted. Separate independentlyacting armatures may however be provided for each pole and the field may be omitted in certain circumstances. The field and armature may be laminated, and, if desired, mounted within the tank. The Specification refers also to repulsion effects on the armatures by the conductor-flux or by eddy-currents, to a subsidiary trip catch, and to contacts actuated by the armature to make a trip circuit.