Sealing end for direct current electric cables

Claim 1

A sealing end installation on a direct current cable, said cable comprising a conductor, a sheath around said conductor and layers of material, including a layer of semiconductive material and a layer of cable insulation, intermediate said sheath and said conductor, said layer of insulation having a resistivity of at least 10 10 ohm-meter, said layers and said sheath being removed from around an end portion of said conductor to provide an end portion of said conductor from which the layers and said sheath have been removed and the sheath and all the layers of the cable outwardly of a length of said cable insulation which is adjacent said end portion of said conductor being removed from around said length of said cable insulation to provide an end of said sheath spaced longitudinally of said cable from said end portion of said conductor and to provide an exposed length of said cable insulation which extends substantially from said end portion of said conductor to said end of said sheath, a hollow container of insulating material which retains liquid disposed around said exposed length of cable insulation, said container having its inner wall spaced outwardly from said exposed length of cable insulation to provide a space between said exposed length of cable insulation and said inner wall for receiving a liquid and said container extending from adjacent said end portion of said conductor to adjacent the end of said exposed length of said cable insulation remote from said end portion of said conductor and having a length longitudinally of said conductor sufficient to withstand the voltage between said conductor and said sheath without breakdown, a liquid having a resistivity in the range from 10 8 to 10 6 ohm-meter in said space between said inner wall of said container and said exposed length of cable insulation and extending from adjacent said end portion of said conductor to adjacent said end of said exposed length of cable insulation remote from said end portion of said conductor, said liquid being free to circulate within said space and to contact said inner wall of said container and substantially all of said exposed length of cable insulation, and said liquid being conductively connected to said conductor at the end of the liquid nearer said end portion of said conductor and being conductively connected at the opposite end of the liquid to said sheath to provide a direct current path through said liquid and from said end portion of said conductor to said sheath which has a resistivity no greater than one-hundredth of the resistivity of said cable insulation, the longitudinal length of said direct current path and the longitudinal length of the exposed length of cable insulation within said container being sufficient to withstand the voltage between said conductor and said sheath without breakdown, and sealing means providing a fluid-tight seal between said sheath and a portion of the container adjacent said end of said exposed length of cable insulation remote from said end portion of said conductor.