Patent GB-511364-A (GB)
Title: Improvements in or relating to a.c. electric circuit-breakers having arc-control devices
IPC: H01H33/75
Filed: 1938-02-16
Abstract: 511,364. Liquid-blast switches. REYROLLE & CO., Ltd., A., and ALLAN, A. Feb. 16, 1938, Nos. 4826/38 and 805/39. [Class 38 (v)] An A.C. circuit-breaker having at least two sets of co-operating contacts immersed in insulating liquid in a tank, has each fixed contact disposed in an arc-control chamber, the several arc-control chambers being constituted by separate compartments in a single insulating structure within the tank. Each compartment has a series of aligned vents through which a blast of deionizing fluid generated by the high pressure produced by the arc in that compartment, is discharged to assist in extinguishing the arc. Figs. 1 and 2 show a 3-phase horizontallywithdrawable unit in which the tank B is suspended from the cover plate A<3> forming the base of the hood A, in which is the operating mechanism of an insulating wall D<2> which carries the three movable bridging-contacts E and separates the two compartments F<3> in each phase. The insulating structure comprises side walls F and front and back walls F<1>, F<2>, through which pass partitions F<4>. The walls and partitions are secured together by bolts F', the front and back walls being lower than the end walls and partitions so as to accommodate the top plates D'. Base plates F<6> extend between the walls F and partitions, and the whole is supported by straps B' from the cover A<3>. The wall D<2> comprises two suitably-spaced plates which are in close sliding engagement with the side walls F, partitions F', top plates D<3>, and bottom plates F<6>, but in order to permit circulation of liquid in the closed position the individual plates are grooved at D<5> and their lower edges lie above the base plates. The walls F<1>, F<2> are formed with one or more vertically-aligned vents F<8> leading into grooves F' just sufficiently wide to receive the ends of contacts E, whereby, and due to the current-loop, the arcs substantially seal the vents and, assisted by the complete closure of each compartment by the movement of the wall D<2>, ensure the building up of the pressure necessary to produce the arc-quenching blast at the current-zero. In the vertical draw-out gear shown in Fig. 3, the tank carries a metal support J<1> for a structure comprising a slotted base plate K', side walls, front and back walls K<2>, K<3>, the inner surfaces of which are formed by stacks of insulating blocks or laminµ K<6> clamped between the side walls and two transverse partitions separating the phases. The cover plates L<2> and blocks K<6> are formed with registering holes to form six conduits K' communicating with the several compartments through vents K<8>, some of the blocks projecting inwards to form slots K' for receiving the contacts E as in Fig. 1. The transverse partitions are vertically slotted to engage corresponding slots in the wall D<2>. Circulating liquid enters the compartments through openings J' in the trough J<3> of the support J<1> and emerges through slots D<3> as in Fig. 1. In a further 3-phase, vertical draw-out arrangement, Fig. 5 the lining M<1> of the tank M is utilized as part of the structure and carries supports M<2> in which are mortised transverse partitions N and side walls. The cover N<4> supports three pairs of insulating tubes O, O<1> carrying the fixed and pivoted movable contacts S, S', and is apertured to receive three actuating rods R<2>, connected to a beam R' operated by solenoids R on the cover M<3>. The front walls N' extending between the partitions N and side walls are each formed with vents N<5> leading to slots N<6> as in Figs. 1 and 3, and the rods R<2> are grooved at R<5> to permit liquid-circulation. The central partitions, as D<2>, may be fixed, and bored to receive vertically-movable rods actuating movable contact rods either arranged in the compartments or entering them from below. The insulating structure may be built of a stack of suitably-shaped plates, or else moulded partially or wholly as an integral unit, the vents being cut, bored, or formed during moulding. Where part of the structure is formed by the tank wall, the other parts may be carried by the lid of the tank or by the insulating bushings.