GB464794A - Improvements in electric cables - Google Patents

Abstract

464,794. Cables. WILLIAMS, A. W. Oct. 25, 1935, No. 29470. [Class 36] In a cable provided with a flexible screening or armour sheath, the outer surface of which is substantially smooth or unbroken, and consisting of two or more helically applied metal strips adjacent convolutions of which overlap, the convolutions 31, 41, 51, Fig. 3, or 10, Fig. 4, are either of the same section but oppositely disposed around the cable, or, as shown in Fig. 2, the convolutions 3, 4, 5, 6 are of different section in which case the strip or strips 6 are preferably of braided or other flexible ribbon. The strips 3, 4, 5 may be positioned on the insulation 17 by grooves 4b into which the insulation 17 is pressed and cords 4c may be provided between the strips 3, 4, 5. Alternatively, the sheath could be formed by applying the strips 3, 4, 5 in the opposite sense, i.e. with their upstanding central portions directed inwardly, over the strips 6. Fig. 5 shows a cable comprising power cores 15, and an earth conductor 16 laid around a rubber centre 18 and separated by rubber strips 19, this assembly being surrounded by an insulating sheath 17 preferably of asbestos or other fire-proof material, enclosed by a sheath 21 constructed according to the invention covered,by a rubber or asbestos sheath 23. The individual insulated cores 15, 16 may be provided with metal sheaths 15c constructed according to the present invention or as described in Specificaton 395,186.