GB385695A - Improvements in electric cables - Google Patents

Abstract

385,695. Cables. BEAVER, C. J., Bell Place, Stamford Road, FAIRFIELD, T. J., Newlands, Talbot Road, both in Bowdon, Cheshire, and GLOVER & CO., Ltd., W. T., Trafford Park, Manchester. Oct. 27, 1931, No. 29745. [Class 36.] To prevent permanent distortion of the lead sheath of a multicore impregnated cable by expansion of the impregnating compound, the sheath is shaped to conform as far as practicable to the external contour of the laid-up cores. As shown in Fig. 1, a three-coil cable having each of the insulated cores 2 wrapped with copper tape 3 is enclosed within a lead sheath 4 of trefoil section which contacts as far as possible with the tape wrappings 3. A protective covering of triangular section and consisting of an armouring layer 6 disposed between layers 5, 7 of jute or hessian is applied over the sheath 4. The sheath 4 is urged into contact with the cable cores by compressible resilient metal paddings 8 which may consist of metal strips having the V-shaped section shown or may be formed by wire helices having circular or triangular cross sections. In a modified construction, Fig. 4, a circular lead sheath 11, reinforced by a metal-tape wrapping 12, is applied over the trefoil-shaped sheath 4 and is protected by layers 5, 6, 7 similar to those shown in Fig. 1. Gas under pressure is applied to the spaces 13 between the sheaths 4, 11, a particularly high pressure being applied momentarily during the manufacture or installation of the cable to ensure good contact of the sheath 4 with the cores 2 and to expand the sheath 11. In applying the sheath 4, the unstranded cores are fed side by side to suitably shaped stationary dies of a lead press, the sheathed cable being drawn off upon a drum which is rotated about the axis of the dies.