GB485408A - Improvements in or relating to air insulated electric cables - Google Patents

Abstract

485,408. Cables. SIEMENS & HALSKE AKT.-GES. March 4, 1937, No. 6506. Convention date, March 5, 1936. [Class 36] An air-space insulated cable comprises one or more lines each consisting of coaxial inner and outer conductors, each inner conductor is constituted by a number of component conductors assembled as strands in direct contact with one another and of such a cross-section that they fit together to form a smooth surfaced conductor of circular cross-section. The component conductors are preferably stranded together with such a long lay, i.e. a length of lay exceeding fifteen times the diameter of the composite conductor, that interfering longitudinal fields are not produced by highfrequency currents flowing in the component conductors. In the construction shown in Fig. 1, an inner conductor 10 comprising sectorshaped strands 11-14 is insulated from an outer conductor 16, consisting of shaped strips, by a helical spacer 14 and a sleeve 15, both formed of a polyvinyl compound such as polystyrol. The strips of the outer conductor are held by a copper binding 17 over which are applied a wound band 18 of insulating material, a water-tight sheath 19 and a flat wire armouring 20 embedded in jute. The strands of the inner conductor, the strips of the outer conductor and the wires of the armouring are laid up in the same direction. The inner conductor may be formed by stranding together three circular wires and then passing the composite conductor through a shaping device in the manner described in Specification 197,692, [Class 36]. Fig. 2 shows a modified construction wherein the inner conductor 21 consists of a circular sectioned wire 22 surrounded by six profiled wires. The inner and outer conductors are separated by spaced insulating discs 23.