GB340303A - Improvements in electric cables - Google Patents

Abstract

340,303. Cables. STANDARD TELEPHONES & CABLES, Ltd. and SCOTT, T. R., Columbia House, Aldwych, London. Sept. 25, 1929, Nos. 29030/29 and 56/30. [Class 36.] In an impregnated paper cable, a reservoir for the impregnating fluid is disposed b e - tween the conductor and the main dielectric, the reservoir acting on the principle described in Specification 291,871, [Class 36, Electricity, Conducting &c.]. The reservoir comprises a layer of absorbent material which is not radially conductive and whose porosity is less than that of the main dielectric. The reservoir is bounded by a metallized surface, the absorbent layer being connected to the main dielectric by wicks of porous material, as described in Specification 337,042, [Class 36, Electricity, Conducting &c.]. A metal tape or a folded strip of metallized paper may be interposed between the reservoir and the conductor. Further reservoirs may be arranged directly under the lead sheath of the cable and at points in the insulation intermediate of the conductor and the lead sheath, in which case the intermediate reservoirs also function as intersheaths to which a potential may be applied. In order to assist in the feeding out of the impregnating fluid from the reservoirs, a narrow belt of highly absorbent paper may be applied over the outside of the reservoirs, either with or without the interposition of a thin layer of normal paper. In the construction shown, a cable comprises a conductor a insulated with sections b, b<1> of dielectric material, such as impregnated paper, enclosed in a lead sheath c. Reservoir layers d, e, f are provided as shown, and belts g of highly absorbent paper are disposed directly on the outside of the inner and intermediate reservoirs d, e. A number of cores provided with reservoirs as described and with earthed screens surrounding each core may be formed into a multicore cable.