GB553716A - Improvements in and relating to electric cables - Google Patents

Abstract

553,716. Electric cables. JOHNSON & PHILIPS, Ltd., and HOLLINGSWORTH, P. M. Jan. 23, 1942, No. 995. [Class 36] The core 1 of an electric cable is surrounded by a thin ductile or flexible sheath 2 of conductive or semi-conductive material, into which gas or fluid is introduced under pressure which is thus transmitted to the surrounding insulant 3 so as to reduce or eliminate the voids or pockets therein. The sheath has physical characteristics nearly identical with those of the insulant. The insulant 3 may consist of a mass of thermoplastic material such as polythene extruded in one or more layers or of layers of textile tape applied helically or longitudinally. The interstices of these layers may be filled with mineral oil, with fluid insulation adapted to set solid, or with a plastic such as polystyrene. The insulant 3 is then covered by a layer 4 of semi-conductive material, a metallic sheath 5, a reinforcement of brass tapes 6 in a bedding of textile material 7 and an outer sheath 8 of lead, lead alloy or plastic material which may be protected by textile tapes 9. The sheath 2 may be used as an electrostatic shield for the core 1. The fluid or gas pressure may be applied to the cable for testing, and then released and re-applied following installation, and should be maintained either wholly or in part whilst the cable is in service.