GB1354572A - Electric cables - Google Patents

Abstract

1354572 Cables BRITISH INSULATED CALLENDERS CABLES Ltd 10 Feb 1972 [11 Feb 1971] 4455/71 Heading H1A An electric cable comprises a conductor having a core dielectric and a conductive or semiconductive layer both of rubber or plastics materials, with a coating of, e.g. graphite dispersed in acrylic resin between the two layers which serves as a release agent to allow the outer layer readily to be stripped. Preferably the graphite coating has a thickness in the range 0À006-0À018 mm. The cable can be made in a single operation by extruding the core dielectric over the conductor, cooling, passing the cable through a bath containing graphite and through a snuggering die to remove excess material, and drying the coating, either in air or forcibly, before extruding the outer conductive layer. It is stated that this method allows the dielectric insulation to be tested, e.g. by discharge scanning and also that, in the cable, corrosion between the conducting coating and outer conductive layer, and the armour of the cable is substantially reduced. Suggested materials for the extrudates are natural rubbers, neoprene (polychlorobutadiene), butyl rubber, silicon rubber, styrene butadiene rubber, ordinary or cross-linked polyethylene and copolymers, e.g. of ethylene and propylene.