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 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.

A composition having an oil film retention function which an oil film can be stably retained on surfaces of various metals, an anticorrosive agent using same, and insulated terminated electric wire. A composition having oil film retention function for being added to base oil to be applied onto a metal surface and retaining base oil on metal surface, and composition contains a component that is an adduct of an azole compound and acidic alkyl phosphate ester including one or more compounds represented by General Formulae (1) (Chemical Formula 1) P(O)(OR.sub.1)(OH).sub.2 . . . (1) or General Formula (2) (Chemical Formula 2) P(O)(OR.sub.1).sub.2(OH) . . . (2) where R.sub.1 represents an organic group having four or more carbon atoms, and component that is an adduct of a metal and/or organic amine compound and acidic alkyl phosphate ester including one or more compounds represented by General Formulae (1) or (2).

A composition having an oil film retention function which an oil film can be stably retained on surfaces of various metals, an anticorrosive agent using same, and insulated terminated electric wire. A composition having oil film retention function for being added to base oil to be applied onto a metal surface and retaining base oil on metal surface, and composition contains a component that is an adduct of an azole compound and acidic alkyl phosphate ester including one or more compounds represented by General Formulae (1) (Chemical Formula 1) P(O)(OR.sub.1)(OH).sub.2 . . . (1) or General Formula (2) (Chemical Formula 2) P(O)(OR.sub.1).sub.2(OH) . . . (2) where R.sub.1 represents an organic group having four or more carbon atoms, and component that is an adduct of a metal and/or organic amine compound and acidic alkyl phosphate ester including one or more compounds represented by General Formulae (1) or (2).

There is provided an insulated electric wire comprising a conductor wire coated by an insulating film, in which the insulating film contains 5 to 20% by mass of a low boiling point component having a boiling point of less than 300 C. under normal pressure. The insulating film preferably has a thickness of 40 to 65 m. The conductor wire preferably has a cross-sectional shape in a rectangular shape or a square shape.

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.

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.

Provided is a transformer oil that has high environmental compatibility and is expected to be further improved in transformer cooling properties. The transformer oil is a transformer oil prepared by mixing a plant oil and a silicone oil and containing no mineral oil, in which a volume ratio of the plant oil to the silicone oil is 3:7 to 7:3 and magnetic particles (for example, temperature-sensitive magnetic particles) are dispersed.

The invention relates to a process for manufacturing a cable comprising at least one electrically insulating layer obtained from a polymer composition comprising at least one polypropylene-based thermoplastic polymer material, at least one dielectric liquid, and at least one thermally conductive inorganic filler, said process involving the mixing of the thermally conductive inorganic filler with the dielectric liquid to form a filler-charged dielectric liquid prior to placing the dielectric liquid in contact with said thermoplastic polymer material.

The invention relates to a process for manufacturing a cable comprising at least one electrically insulating layer obtained from a polymer composition comprising at least one polypropylene-based thermoplastic polymer material, at least one dielectric liquid, and at least one thermally conductive inorganic filler, said process involving the mixing of the thermally conductive inorganic filler with the dielectric liquid to form a filler-charged dielectric liquid prior to placing the dielectric liquid in contact with said thermoplastic polymer material.