Disclosed are an insulation composition that is capable of simultaneously preventing reductions in volume resistance, direct-current dielectric strength, and dielectric breakdown strength due to accumulation of space charges and in which the extent of extrusion of an insulating layer is not reduced, and a direct-current power cable having an insulating layer formed from the same.

Disclosed is an ultra-high-voltage direct-current power cable that is capable of simultaneously preventing or minimizing field enhancement and reductions in high-temperature volume resistance and direct-current dielectric strength due to accumulation of space charges in an insulator.

An electric power cable and a process for the production of the cable including a metal conductor and an electric insulation system surrounding the conductor coaxially and radially outwards of the conductor having improved electric properties. The insulation system includes an inner semi-conducting layer surrounded radially outwards by an insulation layer and wherein the insulation layer is surrounded radially outwards by an outer semi-conducting layer. The electric power cable further includes an inner water blocking material arranged in the conductor and/or to surround the conductor radially outwards and an outer water blocking material arranged radially outwards from the insulation system. An inner barrier layer is arranged as a diffusion hindering layer between the inner water blocking material and the insulation system and an outer barrier layer is arranged as a diffusion hindering layer between the insulation system and the outer water blocking material.

A cable comprising a conductor surrounded by at least an inner semiconductive layer, an insulation layer and an outer semiconductive layer, in that order, wherein the insulation layer is not crosslinked or is cross-linked and comprises at least 90 wt % of a polymer composition, said polymer composition comprising: (I) 95.5 to 99.9 wt % of an LDPE; and (II) 0.1 to 4.5 wt % of an HDPE having a density of at least 940 kg/m.sup.3.

The invention concerns a subsea umbilical comprising an electrical conductor (2) and/or a fluid pipe, and an outer sheath (7) surrounding the electrical conductor (2) and/or the fluid pipe. The umbilical (1, 20, 21, 25, 30, 40, 51, 60) further comprising a plurality of deformable rods (3a, 3b, 15, 23a, 23b, 26a, 27a, 26b) evenly distributed between the electrical conductor (2) and/or the fluid pipe, and the outer sheath (7) for radial load protection of said electrical conductor (2) or fluid pipe.

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 direct-current (DC) power cable. Specifically, the present invention relates to a DC power cable capable of preventing both a decrease in DC dielectric strength and a decrease in impulse breakdown strength due to space charge accumulation, and reducing manufacturing costs without lowering the extrudability of an insulating layer and the like.

An electric cable comprising: a cable core having a radius and comprising an electric conductor and an insulating system; a first metal layer in radially outer position with respect to the cable core; and a semiconductive protecting layer between the cable core and the first metal layer. The insulating system comprises an insulating layer based on a propylene copolymer and the protecting layer is made of non-expanded material and has a thickness of from 0.5% to 3% the radius of the cable core. The cable is apt to safely operate at thermal cycles of from 20 C. to at least 90 C. (for example up to 130 C. or more), with substantially no deformation of the metal layer and of the overall cable structure.

Provided is a semiconductive resin composition which may be used for both an internal semiconductive layer and an external semiconductive layer of a power cable, and in particular has excellent peelability to be used for the external semiconductive layer. In addition, a novel semiconductive resin composition having improved thermal resistance and mechanical physical properties, and an improved deterioration property is provided. The semiconductive resin composition for a power cable includes: 20 to 70 parts by weight of any one or two or more conductive particles selected from the group consisting of carbon black, graphite and graphene, based on 100 parts by weight of a composite resin including a polypropylene homopolymer having a melting point of 150 to 170 C. and an ethylene-(meth)acrylate-based resin.

The invention relates to a semiconductive polymer composition comprising a polymer component, a conducting component and a crosslinking agent, wherein the polymer component comprises a polar polyethylene and the crosslinking agent comprises an aliphatic mono- or bifunctional peroxide or, alternatively, a monofunctional peroxide containing an aromatic group, and the crosslinking agent is present in an amount which is Z wt %, based on the total amount (100 wt %) of the polymer composition, and Z.sub.1ZZ.sub.2, wherein Z.sub.1 is 0.01 and Z.sub.2 is 5.0, an article being e.g. a cable, e.g. a power cable, and processes for producing a semiconductive polymer composition and an article; useful in different end applications, such as wire and cable (W&C) applications.