GB1114325A - Improvements in or relating to electric fuses - Google Patents

Abstract

1,114,325. Fuses. J. R. McCAUGHNA. 1 Feb., 1967 [22 Feb., 1966], No. 7774/66. Heading H2G. An electric current-limiting fuse having a powder-filled cartridge 1 and incorporating a fuse element 6 in the form of ribbon or wire, comprises a mesh-like heat conductive screen 8 disposed within the cartridge in spaced relationship to the fuse element and a heat-dissipating element 9 having a portion exposed to the exterior of the fuse arranged in heatconductive contact with the mesh-like screen, the arrangement being such that the heatconducting screen and dissipating element are electrically insulated from the electrical parts of the fuse. The, or each, of the helically wound fuse elements is wound on a ceramic core 3 of, e.g. porcelain mounted in the cartridge by conductive fittings 4, 5 providing electrical connection of the fuse element to end caps 2. The screen 8 may be of interlinked helical windings forming a unitary structure, formed of copper coated by electro-plating with silver and is spaced by quartz sand 7 from the fuse element and contacts annular heat-conductive washers 9 with exposed surfaces 9a, the washers being electrically insulated by a washer or gasket 10, from the terminals 2. The fuse element may be in the form of ribbon or wire and the washers 9 may be of copper. By this arrangement heat, due to slight over-currents in the fuse, is dissipated and the danger of premature fusion of the fuse element or bursting of the cartridge is avoided.