GB429611A - Improvements in or relating to joints for high tension electric cables - Google Patents

Abstract

429,611. Cable joints. STANDARD TELEPHONES & CABLES, Ltd., and WEBB, J. K., Connaught House, Aldwych, London. Dec. 4, 1933, No. 34022. [Class 38 (i)] High tension cable joints are insulated by filling the joint sleeve with a liquid polymerizable material such as styrene and then polymerizing the material by heating to form a solid mass. The joint 5 may be covered with paper tape 6 impregnated with styrene and covered with metallized paper 7 and enclosed in a lead sleeve 3 having a filling plug 10 at each end. The styrene is then filled into the sleeve under pressure or drawn in by a vacuum pump. If the pencilled surface of the cable insulation 1 is wiped over with a solution of chlorinated diphenyl and a similar chlorinated aromatic hydrocarbon is mixed with the styrene, the joint insulation will weld on to the cable insulation. The heating is carried out at a temperature of 120 to 130‹ C. in an asbestos enclosure 27, Fig. 6, fitted with a heater 25 and thermometer 28, funnels 24 topped up with styrene being fitted to the filler openings. This mode of insulation may be applied to the joints described in Specifications 377,311, 390,208 and 390,817. If applied to an expansion joint as shown in Fig. 4, the flexible conductors 16 and cable ends 4, 4<1> are enclosed in a sleeve 17 which is sealed directly to the cable core 4 and through a bellows 18 to the core 4<1>, an extension 17<1> having a sliding fit with the core 4<1>. The whole of this joint is then moistened with oil, hydroquinone, &c. to prevent adhesion or penetration of the styrene and enclosed to slide in an outer sleeve 19 which is roughened externally to cause the styrene to adhere thereto. In the case of a stop joint, any space between the joint insulation and the lead sleeve is closed by compressing the lead on to the insulation, applying an indiarubber lapping to the insulation, or roughening the interior of the sleeve to cause adhesion of the styrene. Where a sylphon reservoir is used to maintain a supply of oil a valve may be employed that permits free flow into the joint or cable, but partially resists the outward flow during heating.