DIRECT CURRENT CABLE INSULATION WITH INSULATING COMPOSITION INCLUDING ELECTRONEGATIVE GAS

摘要

ABSTRACT OF THE DISCLOSUREA direct current electric cable with a conductor, a semi-conductive screen around and contacting the conductor, aplurality of layers of insulation formed by tapes of insulatingmaterial around the semi-conductive screen, a further semi-conductive screen around the layers of insulation and a metalsheath around the further semi-conductive screen, the layers ofinsulation being impregnated with a non-migrating, insulationcomposition having a dropping point temperature at least 5°Cabove the maximum operating temperature of the cable and havingan electronegative gas dissolved therein, the gas having acoefficient of diffusion in the composition in the range from3 x 10-5 to 3 x 10-6 cm2/sec at temperatures below the droppingpoint temperature of the composition.