GB1484850A - Electric cables - Google Patents

Abstract

1484850 Power cable GENERAL CABLE CORP 28 June 1976 26830/76 Heading H1A In an electric power cable having at least one core made up of a conductor 40, a conductor screen 42, a dielectric wall 44 of plastics material and a dielectric screen 46 and, enclosing the core or cores an outer protective sheath 48, water impermeable isobutylene rubber compound 52 fills the spaces between and adheres to the conductor and conductor screen of the or each core throughout the length of the cable. Where the conductor comprises wires 10 the gaps between the wires are filled with the rubber compound as may be the gap between the dielectric screen 46 and the outer sheath 48. The rubber compound is preferably a low molecular weight polyisobutylene rubber or a low molecular weight copolymer of isobutyleneisoprene rubber. Carbon black or graphite may be add d to the rubber compound (ratios specified) to render it semi-conducting; this semi-conducting material may be used to form the conductor and dielectric screens. The rubber compound is stated to prevent voids being formed between components of the cable during thermal cycling. The dielectric may be of polyethylene, the screens of semi-conducting polyethylene and the sheath may be corrugated metal. Hydrocarbon oil, chlorinated paraffin or isobutylene liquid plastioizer may be added to the rubber compound to facilitate the pumping of its during manufacture. A method and apparatus is described for the manufacture of the cable.