GB495929A - Improvements relating to electric cables - Google Patents

Abstract

495,929. Cables ; impregnating - compositions ; paper. ALLGEMEINE ELEKTRICITATS-GES. Feb. 16, 1938, No. 4877. Convention date, Feb. 16, 1937. [Class 36] [Also in Group VIII] A method of making a cable having layered insulation impregnated by a medium which is originally thinly liquid comprises adding or applying a small quantity of polyisobutylene to the layers, or to filling material in the cable, or to the conductor, or to any two or all of these, so that it mixes with the insulating medium and causes it to thicken in the cable. The polyisobutylene may be applied to one or both sides of some or all of the layers, e.g. of paper, as a solution in xylol, toluol, benzol, benzine or a mixture of these solvents before or during winding ; or, it may be added in solid form to the paper pulp during manufacture of the paper; or, it may be wound on in the form of tape together with the paper tape ; or, strips may be laid between the paper layers ; or, the filling may be coated with or consist entirely or partially of polyisobutylene ; or polyisobutylene or a solution thereof may be introduced into the conductor. The polyisobutylene may be introduced uniformly or zonally into the layers, e.g. into the internal or external layers ; or, it may be introduced into the various layers in different stages of polymerization. The insulation may be under gas pressure. In the Figure, a wrapping c of metallized paper surrounds insulation b treated as. above ; the spaces d are filled with impregnated or unimpregnated filling or, in the case of a gas pressure cable, may be left free or may contain perforated tubes or helical windings. A lead or other waterproof sheath e, metal or insulating-material f and a protective sheath are provided. Specification 473,832 is referred to.