Abstract: An electric power cable line is arranged in which the insulating layer is increased to a greater thickness at two end portions of each cable than a thickness at the other or center portion of the same. Since the insulating layer is increased in thickness at the end portions of the cable, thus an electrical stress exerted on the overall layer construction of the end portions is lowered. Hence, the dielectric strength of the end portions of the cable becomes high and the power cable line will thus be increased in the operational reliability.

Abstract: In a method for manufacturing a stranded conductor for an electrical power cable comprising a process for forming cupric oxide films of from 0.3 .mu.m to 3 .mu.m in thickness by passing an uninsulated stranded conductor constituted by a plurality of stranded copper strands through oxidizing liquid, the stranded conductor passing through the liquid is curved in a wave to form gaps between the strands, and the oxidizing liquid is caused to penetrate between the strands through the gaps to form cupric oxide films of from 0.3 .mu.m to 3 .mu.m in thickness on the surfaces of the strands. Also disclosed is a stranded conductor for an electrical power cable constituted by a plurality of stranded copper strands, at least one of the copper strands being covered with a cupric oxide film free from exfoliation.

Abstract: An apparatus for continuously producing a heat-shrinkable crosslinked resin tube from a crosslinkable resin is provided, comprising in successive connection, an extruder head for extruding the resin into a hollow tube, a fluid under pressure being introduced into the interior of the tube being extruded, a crosslinking cylinder disposed downstream of the head for heating the tubular resin for crosslinking, a flare die disposed downstream thereof for allowing the tube to expand under the fluid pressure, a cooling cylinder disposed downstream thereof for cooling the tube, a guide for deforming the tube into a flattened form, and rollers for pressing and drawing the tube away from the extruder head, wherein a smooth interior surface free of a substantial gap or step extends continuously from the crosslinking cylinder to the cooling cylinder.

Abstract: A laminated insulation paper of the type having two cellulose layers separated by a plastic layer is formed with through holes in the plastic layer such that the respective cellulose layers may contact one another through the through holes. The insulation paper is formed by pressing heated, rounded pins into one of the cellulose layers while backing the other layer until the two cellulose layers are contacted through the hole thus formed in the plastic layer.

Abstract: A method for jointing CV cables includes a lock mechanism which closes a split portion of a mold, used for extrusion-molding and opens the split portion by heat when crosslinking is performed.

Abstract: An apparatus for jointing CV cables includes a lock mechanism which closes a split portion of a mold, used for extrusion-molding and opens the split portion by heat when crosslinking is performed.

Abstract: A DC power cable includes a conductor and an insulation of a thermoplastic resin formed around the conductor. The insulation contains carbon black in an amount of about 0.2 to about 5% of the total weight of the thermoplastic resin and the carbon black, and the ratio of mineral oil absorption (cc/100 g) to specific surface (m.sup.2 /g) in the carbon black is not less than 0.7. The carbon black has the hydrogen content of not more than 0.6% by weight. The specific surface is measured by BET equation. The carbon black has a particle size of 10 to 100 nm.

Abstract: In a method for manufacturing a stranded conductor for an electrical power cable comprising a process for forming cupric oxide films of from 0.3 .mu.m to 3 .mu.m in thickness by passing an uninsulated stranded conductor constituted by a plurality of stranded copper strands through oxidizing liquid, the stranded conductor passing through the liquid is curved in a wave to form gaps between the strands, and the oxidizing liquid is caused to penetrate between the strands through the gaps to form cupric oxide films of from 0.3 .mu.m to 3 .mu.m in thickness on the surfaces of the strands. Also disclosed is a stranded conductor for an electrical power cable constituted by a plurality of stranded copper strands, at least one of the copper strands being covered with a cupric oxide film free from exfoliation.

Abstract: This invention provides an insulating paper sheet produced by mixing synthetic resin flakes with natural fibers to provide a composite paper mass. This insulating paper sheet is favorably accepted as an insulating member for covering the conductor of a power cable.

Abstract: A power cable joint structure in which a sheath isolation is provided in a cable shielding layer in, for instance, each phase of a three-phase circuit. A reinforcing insulation is covered on the connected cable conductors and a shielding layer is covered on the outer periphery of the above-mentioned joint itself. The shielding layer has a pair of mutually opposite layers with a gap therebetween which provides a sheath isolation. A thick sheet-like insulator 12 with a plurality of spherical electrodes distributed therein is contained in the sheath isolation.

Abstract: In the joint structure for a power cable, a cable insulator covers a cable conductor. A reinforcement insulator is mounted on the said cable insulator. In the said reinforcement insulator there are disposed by dispersion a plurality of electrode spheres. The voltage applied in between the said cable conductor and a cable shielding layer covering the said cable insulator is borne by the electrostatic capacities occurring among the said electrode spheres.

Abstract: A POF cable line which comprises a steel pipe and three cable cores drawn in the steel pipe. At least one curved offset section is arranged on the steel pipe at a part spaced from a cable joint at a predetermined distance, with a straight portion of the steel pipe interposed therebetween. The curved offset section prevents the cable cores in the part of the steel pipe from snaking hard and consequently prevents the insulation paper in the part from making soft spots or creases. The snaking occurs easily in the offset section when the cable core thermally expands.

Abstract: Apparatus for continuously vulcanizing a covered material on a conductor comprises a feed device for feeding the conductor in one direction at a constant speed and an extruder for applying the covered material to the conductor fed from the feed means. A vulcanizing tube extends from the extruder, the cable passing through the vulcanizing tube. The vulcanizing tube has a curing section extending from its inlet to a location intermediate its inlet and outlet. A take-off device is disposed forwardly of the vulcanizing tube for hauling the cable. A load applying device is disposed between the extruder and the take-off device for applying a load to the traveling cable at a location forwardly of the curing section of the vulcanizing tube, so that a tension exerted on the cable in a direction opposite to the direction of travel of the cable is applied to the traveling cable.

Abstract: A method is disclosed in which an insulating film of an oxide of metal, of which a stranded conductor (30) is made, is formed on the surface of all strands in a stranded conductor, while the stranded conductor is held in the stranded form. In a step of oxidation-treating the strands of an electric cable the pressure of an oxidation treatment solution at the outer portion of the stranded conductor immersed therein is made higher than the pressure in the inner portion of the stranded conductor (30), causing the oxidation treatment solution (48) to be adequately penetrated from the outer portion into the inner portion of the stranded conductor to permit a desired oxide film to be formed on the surface of all the strands in the stranded conductor.

Abstract: In a method for manufacturing a stranded conductor for an electric power cable comprising a process for forming insulating films by passing an uninsulated stranded conductor constituted by a plurality of stranded conductive strands through oxidizing liquid, the stranded conductor passing through the liquid is curved at an angle of 3.degree. to 10.degree. in a predetermined path to form gaps between the strands, and the oxidizing liquid is caused to penetrate between the strands through the gaps to form oxide films on the surfaces of the strands.

Abstract: Curable polyolefin insulating material covering an electric cable core is continuously cured as it is drawn through a horizontal curing tube constituted of a number of units each composed of heating and cooling zones and a seal portion provided to separate one unit from another, the curing tube being filled with a high-viscosity heat transfer liquid. At each seal portion, the heat transfer liquid is super-cooled and increases its viscosity enough to seal the clearance between the outer surface of the insulated cable core and the inner wall surface of the curing tube to support the cable core with the least dip. This apparatus can improve production efficiency, and the finished product is free of any eccentricity or distortion of its shape.