GB410909A - Improvements relating to liquid-immersed electric switches - Google Patents

Abstract

410,909. Liquid-break switches. COATES, W. A., Walford Lodge, Dunham Road, Bowdon, Cheshire, and ASSOCIATED ELECTRICAL INDUSTRIES, Ltd., Crown House, Aldwych, London. Jan. 18, 1933, No. 1671. [Class 38 (v).] Arc-rupturing devices.-In switches of the kind in which the contacts are liquid-immersed and arranged to provide a plurality of breaks in series in succession, whereby the arc produced at the final break is blown out by a blast produced by pressure generated by the preliminary arc in an explosion pot, a plurality of preliminary breaks in series is caused to occur simultaneously, so that the blast-pressure will be due to a number of arcs and will be adequate to rupture smallcurrent arcs at high voltage. As applied to a multiple cross-jet arrangement in which the blast is forced through a passage 7, across the arc formed in a space 3, and out of passages 4, the upper explosion chamber 13 contains auxiliary fixed contacts 14-20 moulded in recesses in insulating material 24 such as that known under the Registered Trade Mark "Bakelite." Contact 14 is connected by a strap 21 to the central conductor 22 and the remainder are interconnected as shown in Fig. 2, by straps 23. These co-operate with a series of movable contacts 26-32, each of which is spring-pressed towards its co-operating fixed contact and is slidable in a recess in the upper part 34 of a similar moulded insulating block secured on the stem 11 of the spring-pressed contact 10 which co-operates with the moving contact 2. The contacts 26- 31 are interconnected by conductors 41 in channels 39, Fig. 3, and 32 is connected to 11. Thus, when 2 is lowered, the spring 43 holds contact 10 in engagement with it, but a plurality of arcs are formed between the contacts in chamber 13, the current flowing up and down as shown by the full-line arrows in Fig. 1. The number of arcs causes adequate pressure to be developed even when small currents are being broken. By spacing apart the pairs of contacts in a graduated manner, the effect will be obtained that, with larger currents, two or more of the closely-adjacent arcs will coalesce and enhance the blast pressure.