Patent GB-399695-A (GB)
Title: Improvements in or relating to electric circuit breakers having arc-extinguishing structures
IPC: H01H9/36
Filed: 1933-01-31
Abstract: 399,695. Arc-rupturing in switches. WESTINGHOUSE ELECTRIC & MANUFACTURING CO., East Pittsburg, U.S.A.- (Assignees of Lingal, H. J.; 732, Wallace Avenue, Wilkinsburg, Pennsylvania, U.S.A.) Jan. 31, 1933, No. 3035. Convention date, Feb. 16, 1932. [Class 38 (v).] In a " deion " circuitbreaker of the type in which the arc is established adjacent the extinguisher proper and is moved by magnetic action through a converging slot into the extinguishing chamber which includes a plurality of spaced conducting plates, and there subdivided into a plurality of short arcs which are rotated by a radial magnetic field, a plurality of conducting plates alternate with a plurality of insulating plates having central cut-out portions, and means are provided foi spacing the conducting plates to provide venting passages along which the insulating plates completely extend. Fig. 5 shows an exploded view of the structure which comprises a copper base 1, a coil structure 4 for' providing a radial field, a plate structure 18, and a copper end plate 40, the whole being secured by means of a nut 71 screwed on to the. end of a magnetic tube 17 over which is passed an insulating tube 8. An iron polepiece 11 is formed with a depression 12 in which fits an insulating member 16 for the coil 20 which is of copper ribbon. The depression 12 has an opening 15 for one coilend 21 which is bolted at 24 to the base 1, the other end 23 passing through an aperture 28 in an insulating plate 27 and being welded to a copper or other conducting plate 30. The latter fits within a recess formed bv raised portions 54 in an iron plate 50, which is further formed with an inclined slot 52 leading to a cut-away part 53, and with portions 51 for spacing it from the adjacent insulating plate 56. Cut-away parts 57, 58 similar to, but smaller than, those in the plate 50 are formed in the plate 56. The plate structure 18 comprises five composite plates and insulating plates similar to 30, 50, 56, respectively, only one being shown in Fig. 5, the metal parts 60, 70 of the composite plates being slotted in-opposite directions as at 62 to reduce the formation of eddy currents without, however, forming a continuous opening through the structure. The cut-away parts 52, 58, 65 form a narrowing slot along which the arc is driven into the centre part, where it is divided into a number of small arcs and rotated at high speed and so extinguished. The main fixed contact is formed by a part 2 on the base 1, the auxiliary fixed contact is an arc-resisting facing 34 of a raised part 33 of the member 30, and is suitably formed of an alloy 40 per cent silver and 60 per cent tungsten. In the open position, the auxiliary movable contact 7 rests in a recess 41 in the metal plate 40 to which and contacts 6, 7 one lead of the circuit is connected, the other lead being connected to the base 1, Fig. 2. In opening the circuit, the main current path is transferred to contacts 34, 7 by way of the base 1 and coil 20, and when 34, 7 separate, an arc is struck and, in the fully-open position, is transferred to the plate 40. The arc is at once moved into, and restricted by, the slot and subdivided by the plates 60, 70, the plates 50 serving to retain the small arcs within the structure. The extinction is facilitated by the removal of heat through the openings 55, Fig. 5, and the vents 75 formed by means of the spacing projections 51.