GB400838A - Improvements in or relating to electric current interrupting devices - Google Patents

Abstract

400,838. Arc-rupturing in switches. WESTINGHOUSE ELECTRIC & MANUFACTURING CO., East Pittsburg, U.S.A.- (Assignees of Strom, A. P.; 1502, Foliage Street, and Rawlins, H. Le G. ; 710, Coal Street, both in Wilkinsburg, Pennsylvania, U.S.A.) March 21, 1933, No. 8527. Convention date, April 15, 1932. [Class 38 (v).] In arc-extinguishing means for circuit-breakers, fuses, and the like, in which the arc is drawn through a body responsive to the action of the arc to evolve an arc-destroying emanation, the said body is provided with at least two passages of different cross section, one of the passages, having a large cross section, causing the final interruption of the current when the current to be interrupted is' 'large, while another passage, having a small cross section, causes the final interruption when the current to be interrupted is small. In the form shown, an insulating tube 1 carries at its ends a metal ferrule 2 and a tubular metal prolongation 3 adapted to engage contact clips. The tube is packed with material 17 which, when exposed to an arc, gives rise to a gas or other arc-destroying emanation. This material may be boric acid (which evolves water) in the form of cakes or bricks, or soapstone cylinders or discs, or alternate discs of fullerboard and asbestos soaked in oil. A passage 18 of large cross section in the material 17 accommodates a conductor 7 which is connected at its upper end to a fuse 12 carried by the ferrule 2, and at its lower end through flexible conductors 14, to the tubular extension 3. A narrower passage 21 accommodates a fine wire conductor 22, connected at its lower end to the conductor 7 and at its upper end to the fuse 12 or ferrule 2. When the fuse 12 melts, the conductor 7 is withdrawn into the passage 18 under the action of a spring 11. If the current interrupted is small, the wire 22 carries current until the conductor 7 has been withdrawn a sufficient distance to extinguish any arc that may have been formed in the wider passage 18. The wire 22 then fuses, and the final arc formed thereby is extinguished in the narrow passage 21. If the current interrupted is large, the wire 22 fuses almost instantaneously, and the final extinction of the arc takes place in the passage 18. In modifications, the wire 21 is not connected at its upper end to the fuse 12 or ferrule 2, but extends freely into the space where the arc is formed, or is connected to a washer adjacent thereto, so that the arc jumps to the wire 22 as soon as the fuse 12 melts. Instead of initiating the arc by the melting of a fuse, the upper end of the conductor 7 may extend between two switch blades and be held by a latch provided with tripping means.