Provided is a power cable, particularly, an ultra-high voltage underground or submarine cable for long-distance direct-current transmission. Specifically, the present invention relates to a power cable which includes an insulating layer of high dielectric strength, is capable of uniformly and effectively alleviating an electric field applied to the insulating layer, is particularly structurally stable, has high flexibility, and is capable of suppressing partial discharge, dielectric breakdown, etc. of the insulating layer, thereby increasing the lifespan and productivity of the cable.

A power cable includes a conductor, an inner semi-conductive layer covering the conductor, an insulating layer covering the inner semi-conductive layer and impregnated with insulating oil, an outer semi-conductive layer covering the insulating layer, a metal sheath layer covering the outer semi-conductive layer, and a cable protection layer covering the metal sheath layer. A minimum thickness t1 of a certain cross section of the metal sheath layer is less than or equal to 90% of a maximum thickness t2 thereof.

Provided is a power cable, particularly, an ultra-high voltage underground or submarine cable for long-distance direct-current transmission. Specifically, the present invention relates to a power cable which includes an insulating layer of high dielectric strength, is capable of uniformly and effectively alleviating an electric field applied to the insulating layer, is particularly structurally stable, has high flexibility, and is capable of suppressing partial discharge, dielectric breakdown, etc. of the insulating layer, thereby increasing the lifespan and productivity of the cable.

A power cable includes a conductor; an inner semi-conductive layer covering the conductor; an insulating layer covering the inner semi-conductive layer, the insulating layer being impregnated with an insulating oil; an outer semi-conductive layer covering the insulating layer; a metal sheath layer covering the outer semi-conductive layer; and a cable protection layer covering the metal sheath layer. The insulating layer is formed by cross-winding insulating paper and impregnating the insulating paper with the insulating oil. The inner semi-conductive layer and the outer semi-conductive layer are formed by cross-winding semi-conductive paper and impregnating the semi-conductive paper with the insulating oil. A thickness of the outer semi-conductive layer is 7.5 to 15% of a total thickness of the inner semi-conductive layer, the insulating layer, and the outer semi-conductive layer.

Provided is a power cable, particularly, an ultra-high voltage underground or submarine cable for long-distance direct-current transmission. More specifically, the present invention relates to a power cable, in which an insulating layer has high dielectric strength, an electric field applied to the insulating layer is effectively reduced, and particularly, a void is suppressed from occurring in the insulating layer due to contraction of insulating oil, caused by a decrease of temperature in the insulating layer under a low-temperature condition or when the supply of an electric current is stopped, thereby effectively suppressing partial discharge, dielectric breakdown, etc. due to an electric field concentrated in the void.

Provided is a power cable, particularly, an ultra-high voltage underground or submarine cable for long-distance direct-current transmission. More specifically, the present invention relates to a power cable, in which an insulating layer has high dielectric strength, an electric field applied to the insulating layer is effectively reduced, and particularly, a large void is suppressed from occurring in the insulating layer when the power cable is left at low temperatures for a long time until electric current is supplied thereto after installed in a low-temperature environment, thereby effectively preventing partial discharge, dielectric breakdown, etc. from occurring due to an electric field concentrated in the large void.

A power cable includes an insulation layer, itself, having high dielectric strength. An electric field to be applied to the insulation layer is effectively buffered, degradation of the insulation layer can be prevented during a cable connection step such that the life of the power cable is extended and simultaneously, the thickness of the insulation layer is minimized such that an outer diameter of the cable is reduced, thereby enabling flexibility, ease of installation, workability and the like of the cable to be improved.

The present invention relates to electrical cables, particularly high voltage cables, comprising a biodegradable fluid to act as an electrical insulating material. The electrical cables may be located overground, in subterranean environments, or under waterways.

The present invention relates to a power cable and, particularly, to an extra-high voltage underground or submarine cable. Particularly, the present invention relates to a power cable in which an insulation layer, itself, has high dielectric strength, an electric field to be applied to the insulation layer is effectively buffered, degradation of the insulation layer can be prevented during a cable connection step such that the life of the power cable is extended and simultaneously, the thickness of the insulation layer is minimized such that an outer diameter of the cable is reduced, thereby enabling flexibility, ease of installation, workability and the like of the cable to be improved.

A high voltage direct current cable includes at least one electrical conductor, at least one semiconducting layer, at least one stratified insulation made from windings of at least one paper-polypropylene laminate, the stratified insulation being impregnated with at least one electrically insulating fluid having a kinematic viscosity of at least 1,000 cSt at 60EC, wherein the laminate includes at least one paper layer having an air impermeability of at least 100,000 Gurley sec.sup.1. Such a high air impermeability of the paper layer(s) remarkably reduces the swelling of the polypropylene layer(s) during impregnation with a high viscosity insulating fluid, thus preventing delamination, up to the end of the impregnation process for the whole stratified insulation.