GB529649A - Improvements in or relating to electric communication cables - Google Patents

Abstract

529,649. Cables. STANDARD TELEPHONES & CABLES, Ltd., MORLEY, J. F., and NUNN, D. May 24, 1939, No. 15362. [Class 36] Air - space insulated communication cables, such as coaxial conductor cables and screened pairs or quads have the air spaces built up by one or more composite insulating cords, each consisting of a one or more central cones 1, Figs. 1 and 2; of cotton, esterified cotton, silk, artificial silk, or other flexible and non-extensible fibrous insulating-material, surrounded by a sheath 2 of normally extensible insulating material. The cords may extend longitudinally or helically of the cable conductors. Fig. 3 shows a coaxial conductor cable in which the inner conductor 3 is spaced from the outer conductor 5 by a helical composite cord 1, 2 surrounded by a lapped or extruded insulating sheath 3. In a screened pair cable each conductor may be lapped with an open winding of composite cord and surrounded by an insulating sheath, the insulated cones thus formed being laid up with fillers, which may be of the same form as the cords, and enclosed in a common insulating jacket over which is disposed the screen, the latter being surrounded by insulating or metallic tapes and a lead sheath. Screened quad cables may be similarly formed, the four insulated cones being disposed about a central starshaped insulating filler, preferably provided with a fibrous cone. The insulating sheath of normally extensible material of each composite cord is preferably formed of a material having a power factor less than 0.0008. Several materials having these properties and consisting of a mixture of polystyrene and rubber, with or without wax, polysobutylene, talc and polyethylene, are described.