GB436295A - Improvements in electric cables - Google Patents

Abstract

436,295. Cables. CALLENDER'S CABLE & CONSTRUCTION CO., Ltd., and HUNTER, P. V., Hamilton House, Victoria Embankment, London. April 6, 1934, No. 10518. [Class 36] To prevent draining of the impregnating compound from the impregnated dielectric into the gas-space in a cable of the kind comprising one or more cores having impregnated insulation and in which a space containing gas is provided between the insulated cores and the cable sheath, each insulated core is enclosed in a close fitting layer of flexible non-metallic material which is impermeable to the impregnating medium and the cores are formed with a non-circular cross-section so that expansion of the impregnating compound is accommodated by a bending, rather than a stretching, of the impermeable non-metallic layer. The impermeable layer may be formed from a cellulose derivative, an olefine polysulphide product, a pitch, a phenolic or other resin, or a lapping of oiled silk. In the construction shown, a conductor 1 of elliptical cross-section has a layer of impregnated paper insulation 2 which is enclosed in an impermeable layer 3. The core thus formed is wound with a conductive strip 4 and is enclosed in a circular lead sheath 5, the spaces 6 between the core and sheath being filled with air, nitrogen, or helium under atmospheric or higher pressure. In another construction, three cores having impermeable layers and wound with conductive strip are laid up with loose fillers and enclosed in an over size lead sheath, the free space within the sheath being filled with air. Specifications 358,190 and 361,930 are referred to.