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.

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.

An electricity transmission cable with mass-impregnated paper insulation has around at least one conductor (1), an impregnated paper layer (2) and a metal layer (3) adjacent to the impregnated paper layer, this metal layer (3) consisting of copper or aluminum. The cable has, directly around said metal layer (3), an insulating material layer (4) and, directly around the insulating material layer (4), a transverse reinforcement layer (5) made of steel or made of glass fiber tape.

The invention relates to an electricity transmission cable with mass-impregnated paper insulation comprising around at least one conductor (1), an impregnated paper layer (2) and a metal layer (3) adjacent to said impregnated paper layer, this metal layer (3) consisting of copper or aluminium.

According to the invention, the cable comprises, directly around said metal layer (3), an insulating material layer (4) and, directly around said insulating material layer (4), a transverse reinforcement layer (5) made of steel or made of glass fibre tape.