GB1309248A - Jointing and terminating electric cables - Google Patents

Abstract

1309248 Moulding electrical insulation PIRELLI GENERAL CABLE WORKS Ltd 8 Dec 1970 [11 Dec 1969] 60488/69 Heading B5A [Also in Division H2] A method of jointing or terminating electric cables comprises the steps of stripping the cable insulation, electrically connecting the cable conductors or the cable conductors and the terminals, enclosing the connection in a mould, at least over the region from which the insulation has been stripped, and introducing into the mould foamable plastics material, and filler material, the plastics material then foaming to fill the mould and encapsulate the cables. The filler material has a greater thermal conductivity than the foamed and cured plastics material. In one arrangement the filler material is introduced first followed by the foamable plastics material. In a second arrangement the filler material and the foamable plastics material are mixed initially and then introduced into the mould. In a third arrangement part of the filler material is placed in the mould and the remainder is mixed with the foamable plashes material, the mixture then being introduced. In the arrangements in which part of or the whole of the filler material is introduced first it may comprise granular material, e.g. high-density polyethylene, PVC or glass, in the form of microballoons, or a sheet or tape of mesh material, e.g. polyethylene or glass. In the third arrangement the remainder of the filler material comprises granules of a size smaller than the granules or spacings in the mesh of the first part of the filler material. These smaller granules, which are also used in the second arrangement, are carried by the foam as it expands and are distributed throughout the mould. Examples given are sand, slate, PVC or polyethylene, in flow form, or glass, in the form of microballoons. The foamable plastics material, which can be polyurethane, epoxy, polystyrene, polyester or polypropylene, is subjected to pressure as it foams, for example it may have a greater potential volume than that available for its expansion. The conductors, and, when terminating a cable, the terminals, may be insulated prior to the introduction of the foamable plastics material.