GB439575A - Improvements in electric cable installations - Google Patents

Abstract

439,575. Cables; cable joints. CALLENDER'S CABLE & CONSTRUCTION CO., Ltd., BRAZIER, L. G., and ROBINSON, D. M., Hamilton House, Victoria Embankment, London. June 7, 1934, No. 16907. [Classes 36 and 38 (i)] In a cable having impregnated paper insulation, the body of insulation is divided into two coaxial portions by a layer of material impervious to the impregnating materials present in the cable and the inner portion is flooded with mobile impregnating liquid which is supplied under pressure through the conductor of the cable from external reservoirs. The outer portion of the insulation is impregnated with a thicker liquid and does not communicate with a reservoir. The cable may be a stranded conductor 1, Fig. 3, having layers 2, 4 of insulation which are separated by an impermeable wrapping of oil silk tape 3, the insulating layer 4 being surrounded by a wrapping of metallized paper tape 11 which placed in electrical contact with the cable sheath 5 by a wrapped textile tape 12 containing interwoven copper wires. In modified constructions the impermeable layer consists of benzyl cellulose, or cellulose acetate and is applied by extrusion. Mobile insulating liquid is supplied to the insulating layer 2 through the interstices between the strands of the conductor. Fig. 1 shows an installation embodying the invention comprising two lengths of cable, a joint 6 and two alternative forms of terminal structure. The joint 6 is so formed as to preserve the continuity of the layers 2, 3, 4 between the two cable ends connected by the joint, and the two conductors 1 are connected together in a manner which does not cause blockage of the spaces between the conductor strands. The terminal structure shown at the left hand side of the Figure comprises a porcelain insulator 9 surrounding the cable end and filled with mobile insulating liquid which is maintained under pressure by a pressure reservoir 13 and which is in communication with the liquid contained within the inner layer of the cable insulation. The lead sheath 5 at the cable end is terminated by a stress cone 15, above which is applied insulation 16. An impermeable layer 17, which is connected at its upper end to the layer 3, is applied over the insulating layer 4 of the cable end to isolate this layer from the liquid within the insulator 9. The conductor 1 is connected to a terminal member 10 bv a flexible connection 14. In the construction shown at the right-hand side of the Figure,. the impermeable layer 17 is omitted and the insulator filled with viscous compound similar to that used in the insulating layer 4 of the cable, the insulating layer 2 being closed by a cap 19 which communicates with the pressure reservoir 13 containing the mobile liquid. The reservoir 13 may be exterior of the insulator, as shown, or may be arranged directly on the end of the conductor within a metal dome mounted on the top of the insulator.