GB460591A - Improvements relating to electric cables - Google Patents

Abstract

460,591. Cables. SIEMENS BROS. & CO., Ltd., and FOSTER, A. E. July 31, 1935, No. 21737. [Class 36] A cable of the air-space type comprises a tube of low loss thermoplastic insulating material, such as polystyrol, surrounding a conductor which is centred within the tube by being formed at intervals along its length with projections, e.g. of wave shape, which locally bear on substantially diametrically opposite points of the inner wall of the tube. The tube mav be surrounded by a screen or return conductor formed of metal strip, and may be sheathed with lead. A plurality of cables,. with or without individual metallic coverings, may be enclosed by a common sheath. The Figure shows a conductor 1 having spaced wave-like projections 2 which support the conductor centrally within a tube formed of wrappings 3a, 3b, 3c of polystyrol or a mixture of polystyrol and a plasticizer. The wrappings 3a, 3b, which are in opposite directions, are applied with a long lay. A return conductor or screen, consisting of copper strips 4 held in place by a copper tape binding 5, is applied over the wrapping 3c. A lead sheath b, surrounded by armouring wires 8, embedded in jute servings 7, 9, complete the cable. Successive projections 2 may be staggered about the axis of the conductor. In a modified construction the wrappings 3a, 3b, 3c are replaced by an extruded tube. Specification 452,772 is referred to.