GB644541A - Improvements in insulated electric power cables - Google Patents

Abstract

644,541. Oil-filled cables. GENERAL CABLE CORPORATION. July 16, 1948, No. 19209. Convention date, July 23, 1947. [Class 36] An impregnated paper insulated cable is provided with impermeable and non-absorbent wrappings to prevent drainage of oil from the insulation and to prevent the entrance of moisture. The cable is provided with skid wires to enable it to be pulled through a pipe which is then filled with insulating fluid under pressure. The Figure shows a cable consisting of a conductor 11 surrounded by oil-impregnated paper 12 which may be wound over metallized paper tapes or other conducting or semiconducting tapes covering the conductor 11. An electrostatic shielding screen 13 which may consist of a helically wrapped metal tape covers the insulation 12. The wrappings which prevent drainage of oil from the paper insulation 12 comprise in the construction shown in the figure overlapping tapes 15, 16 of copper or aluminium and polyethylene respectively, and two further metal tapes 17, 18. The tapes 15, 16 may be replaced by a single polyethylene tape, or two tapes, both of synthetic material, for example nylon or polytetrafluoroethylene, may be used. The tapes 17, 18 are of metal or other material which stretches less easily than the material of the underlying tapes 15, 16. Before the cable is installed in a pipe it may be kept under internal pressure by connection to a reservoir containing oil or an inert gas such as nitrogen under pressure. The skid wires 19 are approximately semi-elliptical in crosssection. Specifications 393,292 and 471,590, [Group IV], are referred to.