GB479850A - Improvements in or relating to liquid-insulated electric circuit-breakers - Google Patents

Abstract

479,850. Liquid-break - switches. REYROLLE & CO., Ltd., A., and ALLAN, A. Aug. 11, 1936, No. 22091. [Class 38 (v)] In a liquid-insulated circuitbreaker of the kind having a pair of fixed contacts mounted in arc control devices comprising insulating enclosures through which the movable contacts are drawn on opening the circuit and in which a high pressure is produced by the arc so that the arc products are discharged through lateral vents in the enclosures, the enclosures and movable contact rods are made of arcuate shape, and the movable contact rods are rotated to open the circuit by a vertically slidable operating member actuated from outside the tank or chamber containing the circuit-breaker. In the construction shown, the arc control devices A are arranged in a vertical plane and are supported by insulators B<2> from the top-plate BI of the tank B. The fixed contacts consist of a number of pairs of spring-controlled contact-blocks D connected by conductors A<2> to lead-in conductors mounted in insulator bushings A<4>. The outer pair of contact-blocks D<2> is extended beyond the others, and the final separation of the contacts takes place between this pair and a renewable arcing tip on each of the movable contact rods E. The latter are carried by levers E<2> pivoted at E<3> and connected by links C<1> pivoted at C<2> to the lower end of the operating rod C. The latter is surrounded by an insulating cylinder G housing a throw-of spring, and is actuated from outside the tank by a rack-andpinion mechanism C4 or other means. The arms E<2> are bifurcated to allow the operating rod to pass between them and to permit the two arms to cross as they pass to their respective pivots. A short upwardly directed cylinder C<3> on the rod C co-operates with a fixed member to give a dashpot action at the end of the closing movement, and a similar dashpot may be provided to operate at the end of the opening movement. Each arc control device comprises a pair of side plates F between which are clamped blocks F<2>, F<3>, each of which, in the form shown, is built up of a pair of plates. The block F<2> is provided with a series of vents F<5> extending to the outside of the structure from a groove F<6> in the inner wall of the block. The outer edge of the movable contact rod E fits in the groove FI with the minimum clearance necessary for free movement, so that in the closed position of the circuit-breaker it serves substantially to close the vents F<5>. The arrangement is such that the current flow tends to deflect the arcs into the vents ; if desired, this action may be increased by embedding pieces of magnetic material in the blocks F<2> in the neighbourhood of the vents. In a modification, the arc control devices are mounted horizontally and the movable contacts are carried by a cross-bar which is rotatable about the axis of the operating rod. For this purpose, the latter may be provided at its lower end with a helically-twisted portion of square cross-section which engages a squared hole in the cross-bar, whereby vertical movement of the operating rod imparts a rotary movement to the cross-bar. Specifications 435,308 and 452,146 are referred to.