GB134290A - Improvements in Electric Fusible Cut-outs. - Google Patents

Abstract

134,290. Trent, H. E. Oct. 28, 1918. Fusible cut-outs.-Fuse wires or strips of lead or zinc are covered at intervals along their length with a compound of good heat distributing and dissipating qualities but of poor electrical conduotivity, so as to reduce the temperature of the fuse at the covered parts and ensure fusion first at the uncovered parts. A covering having these properties may contain a minimum of vaporizable material, and the covering itself may serve to cushion the effects of the explosion. In the arrangement shown in Fig. 1 applied to a strip cartridge fuse, the strip, which is of uniform cross-section, is covered at 7, 8, 9 with a mouldable compound made of asbestos fibre, manganese dioxide, feldspar, and plaster of paris, mixed together with silicate of soda to form a paste. The strip may be reduced in width at the exposed parts. A compound fuse may be made up of a number of wires connected in parallel to terminal blocks, all the wires being covered together, at intervals, with the compound. A cartridge fuse made up of a single wire covered as described may be under spring tension. A single wire may be enclosed by a tube of the compound, the tube having perforations at intervals so as to leave the wire substantially uncovered at these intervals. The tube may be covered by an outer tube of asbestos or shellaced paper.