GB517225A - Improvements relating to electric cables and other electrical conductors - Google Patents

Abstract

517,225. Cables. BRIGG, J. E. July 19, 1938, Nos. 21441/38 and 20688/39. [Classes 36 and 38 (i)] To prevent ionization in the spaces between the conductor a and the innermost layer of laminated dielectric b in a high-tension cable, joint, or bushing the spaces are screened by composite metallic and insulating tapes so arranged that no exposed metallic edges or surfaces thereof are presented to the innermost dielectric layer. As shown in Fig. 2 a paper tape d, with or without a metallized inner surface f, is lapped on the conductor, the spaces e between the turns of the tape being screened by a further wrapping of metallized paper tapes g which is so folded that the metal coating h is almost completely enclosed. The coating h is conductively connected to the conductor at intervals. The conductor may be provided with a smooth surface as described in Specification 454,449. The screening tape g may be formed by coating a metal tape with insulating material. A single metallized paper tape may be folded in such a manner as to form a double-thickness screening tape, similar to the tape g, mechanically and electrically connected to a single-thickness underlying tape similar to the tape d. Fig. 4 shows one such method of folding the tape, whilst Fig. 6 shows a construction wherein the tapes d, g are of similar cross-section. The tapes may be applied longitudinally of the conductor instead of helically. The outer surface of the dielectric may also be screened in a similar manner. Specification 517,225 also is referred to.