GB1254008A - Improvements in or relating to telecommunication cables - Google Patents

Abstract

1,254,008. Telecommunication cables. BRITISH INSULATED CALLENDER'S CABLES Ltd. 6 Feb., 1970 [21 Nov., 1968; 21 Nov., 1969], Nos. 55337/68 and 5864/70. Addition to 995,582. Heading H1A. In a telecommunication cable having a plurality of conductors, each with a cellular plastics dielectric, enclosed in a waterproof sheath, the interstices between the insulated conductors and between them and a surrounding covering which may, or may not be, the cable sheath are filled from end to end with a water-impermeable cellular material, e.g. a polyurethane foam, in which the cells are non- interconnecting. The conductor dielectric may consist of cellular polythene or cellular polypropylene. The cable may be of " layer " or " unit " construction with the conductors arranged in groups and the surrounding covering when not the cable sheath constituted by belt papers, plastics, tapes or metal or metal/ t plastics foil forming an electrical screen or a water barrier. Where the covering is separate from the cable sheath, the latter is applied so that no interstices are formed between them. Where the conductors are arranged in more than one group, the interstices between the groups and between the groups and the sheath may also be filled with foamable material. The filling material may be introduced in a non-cellular condition in a single operation or in stages as the conductors are being stranded together, e.g. before or after a layer of conductors is applied to an underlying assembly. The expansion of the filling material into cellular form may take place during extrusion of the cable sheath. The conductors may be of copper, aluminium or aluminium alloy.