GB619239A - Improvements in or relating to electric fuses or cut-outs - Google Patents

Abstract

619,239. Cut-outs. MULLER, H. Nov. 1, 1946, No. 32445. [Class 38 (i)] A fuse comprises a mass of iron B in proximity to a fusible wire A which is stretched over two sharp-edged members F, G. A large current in the wire A magnetizes the iron B which attracts the wire and facilitates its rupture. The wire may be supported by several members similar to the members F, G arranged at intervals along the insulating base C. Fig. 4 shows a modification in which the wire passes round two sides and one end of the base which is provided with an iron mass B between the two side portions of the wire and a sharp projection H at one end. The wire may completely encircle the base which is then provided with a projection at each end. The iron B may be replaced by a permanent magnet which projects at right angles from the base. The wire is attracted towards the magnet for only one direction of the current. Fig. 7 shows a further modification in which a permanent magnet B is placed in the same position as the iron in Fig. 1. The wire in this construction passes through an opening in a mica bridgepiece H which produces a shearing force on the wire when a large current passes. Instead of a single piece of iron several pieces may be arranged on opposite sides of the wire alternately, the wire passing through apertures in a number of bridge-pieces. Fig. 10 shows two iron masses B, B1, on opposite sides of a wire A which passes through an opening in a bridgepiece F. The opening has sharp edges K, L. A three-phase circuit may be provided with a fuse comprising three wires on one side of an iron mass or two wires on one side and one on the other, all the wires passing over sharp rupturing edges.