GB501593A - Improvements in or relating to electric cables - Google Patents

Abstract

501,593. Cables. O'DUFFY, D. A. Aug. 27, 1937, No. 23514. [Class 36] A high-tension cable having a paper, fabric, or other porous dielectric, which may or may not be impregnated with oil or compound, and of which the interstices are filled with gas under pressure, has provided therein, but outside the electric field, material capable of absorbing moisture from the gas-filled dielectric, suitable materials being activated carbon, calcium chloride, silica gel, calcium sulphate, soda lime, and phosphorus pentoxide, and a mixture of calcium oxide and hydroxide. The material may be inserted in pellet, granular, or sheet form and may be held in position by a binding agent. Alternately, the material may be in containers, for instance, of paper. In the construction shown in Fig. 2, porous walled capsules 6 containing moisture -absorbing material are located at intervals in a braided cotton tube 5 extending within a helical metal strip 4 upon which a hollow conductor 1 is stranded. Impregnated paper insulation 2 and a lead sheath 3 surround the conductor 1, and the cable thus formed is charged with gas under pressure. In a modified construction, Fig. 4, the inner surface of the lead sheath 23 has longitudinal grooves 27, in one or more of which capsules 26 of the absorbent material located in a braided cotton tube 25 are disposed, the outer surface of the dielectric being metallized so that the absorbent material is not subjected to electric stress. In another construction braided tubes containing capsules of absorbent material are located in the jute or other fillers occupying the spaces between the screened cores of a three-core cable.