Method of joining of insulated high-voltage cables

Claim 1

A method of joining two lengths of cables having a central conductor surrounded by an inner layer of semi-conducting material which is in turn surrounded by an outer layer of solid polymer material, said method comprising the steps of stripping an end of each cable down to the central conductor whereby an end portion of each central conductor is exposed and the layer of semi-conducting material and layer of solid polymer material taper to form two frusto-conically shaped insulation ends; fixed by joining in a smooth abutting relationship the end portions of the central conductors; winding tape of semi-conducting material about the stripped end portions of the central conductors and in contact with the taper of the inner layer of semi-conducting material so as to form thereupon a first layer of semi-conducting material having substantially the same thickness as the inner layer of semi-conducting material on the cable whereby there is a smooth uniform transition from the inner layer of one cable to the inner layer of the other cable; then wrapping a tape of vulcanizable insulation material about the layer of semi-conducting material and the tapered portion of the outer layers so as to form a second layer substantially flush with the peripheral outline of the cable insulation; positioning against the formed second layer a plurality of axially extending metal strips, the metal strips longitudinally spanning and peripherally surrounding the formed second layer to form a third layer which is axially rigid; wrapping circumferentially around the third layer of metal strips an elastic element which lies pressure directed radially inward on the metal strips; removably jacketing said third layer with heating means; heating the layer of insulation tape to a temperature and for a period of time for causing vulcanization of the insulation tape forming the second layer; removing the heating means when vulcanization is completed; and finally removing the elastic element and the metal strips.

Claim 2

A method of joining two lengths of cables having a central conductor surrounded by an inner layer of semi-conducting material which is in turn surrounded by an outer layer of solid polymer material, said method comprising the steps of stripping an end of each cable down to the central conductor whereby an end portion of each central conductor is exposed and the layer of semi-conducting material and layer of solid polymer material taper to form two frusto-conically shaped insulation ends; fixed by joining in a smooth abutting relationship the end portions of the central conductors; winding tape of semi-conducting material about the stripped end portions of the central conductors and in contact with the taper of the inner layer of semi-conducting material so as to form thereupon a first layer of semi-conducting material having substantially the same thickness as the inner layer of semi-conducting material on the cable whereby there is a smooth uniform transition from the inner layer of one cable to the inner layer of the other cable; then wrapping a tape of vulcanizable insulation material about the layer of semi-conducting material and the tapered portion of the outer layers so as to form a second layer substantially flush with the peripheral outline of the cable insulation; positioning against the formed second layer a plurality of axially extending metal strips, the metal strips longitudinally spanning and peripherally surrounding the formed second layer to form a third layer which is axially rigid; wrapping circumferentially around the third layer of metal strips an elastic element which lies pressure directed radially inward on the metal strips; removably jacketing said third layer with heating means; heating the layer of insulation tape to a temperature and for a period of time for causing vulcanization of the insulation tape forming the second layer; removing the heating means when vulcanization is completed; and finally removing the elastic element and the metal strips.