GB495034A - Improvements in or relating to electric conductor cables - Google Patents

Abstract

495,034. Cables. STANDARD TELEPHONES & CABLES, Ltd., and SCOTT, T. R. May 4,1937, No. 12708. [Class 36] A cable for simultaneously transmitting high tension and high-frequency currents comprises a pair of coaxial conductors separated by insulating spacing means consisting of extruded insulating layers arranged directly over and under the inner and outer conductors respectively, which layers are spaced apart by insulating-material which is maintained directly under gas pressure, i.e. gas under pressure permeates the space between the two layers. The extruded layers may be formed of a polymerized aromatic mono-olefine, such as polystyrene, or polyisobutylene, admixed, if desired, with rubber or plasticizers, or both. The surfaces of the layers acted upon by the gas may be rifled. One or both extruded layers may be of composite formation comprising two insulating layers separated by a conducting layer which is connected to the adjacent inner or outer conductor at joints in the cable. The conducting layer of the outer composite layer may be used as an intersheath. The insulation between the extruded layers may comprise fibrous material such as paper, unacetylated or acetylated and, if desired, impregnated with polystyrene, the material being applied as a lapping, or the 'insulation may be in the form of washers, or helical windings of textile cords or polystyrene filaments or tubes. In the construction shown in Fig. 9, a central stranded conductor 1 surrounded by an extruded insulating layer 2 is spaced from an extruded insulating layer 12 arranged on the inner surface of an outer conductor 13 by helical insulating cords 11<1>. A lead sheath 10 surrounds the outer conductor and gas under pressure fills the free spaces between the layers 2, 12. In a modified construction the layers 2, 12 are separated by lappings of paper, the layers of paper being spaced apart, if desired, by helically applied tubes or cords of cotton or polystrene. As shown in Fig. 11, shaped insulating strips 16 separate the extruded layers 2, 12. A plurality of insulated cores may be combined into a multicore cable with belt insulation. Specifications 417,929, 459,518, 461,677, 479,883, and 494,695 are referred to.