Sumitomo Electric Industries, Limited

Other

Hiroshi Takigawa

Ryosuke Hata

Jun Yorita

Masayuki Hirose

Yuuichi Ashibe

Hidemitsu Kuwabara

Morihiro Seki

Mamoru Kondo

Takahiro Horikawa

Yuichi Ashibe

Ken Yatsuka

Katsuhiko Katayama

Toru Tsujioka

A dielectric strength test method of a superconducting cable that can evaluate the insulation characteristic of a superconducting cable in a state in which a refrigerant is filled without filling a refrigerant is provided. A tested superconducting cable is filled with gas in place of a refrigerant and a regular dielectric strength test is conducted at room temperature. Preferably, a preliminary dielectric strength test is conducted prior to the regular dielectric strength test. In the preliminary dielectric strength test, a first reference superconducting cable filled with a refrigerant at a predetermined pressure and a second reference superconducting cable filled with gas in place of a refrigerant at a predetermined pressure are provided. The preliminary dielectric strength test is conducted for the first reference superconducting cable at refrigerant temperature and the second reference superconducting cable at room temperature to find the correlation between the dielectric strength characteristics of the cables. At the time, the test voltage is determined based on the dielectric strength characteristic of the second reference superconducting cable. The regular dielectric strength test is conducted at the test voltage.

Dielectric strength test method of superconducting cable

A joint for a superconducting cable joints superconducting cables with one another. The superconducting cable comprises a former, superconducting conductor, and insulating layer. The construction of the joint comprises the following steps: preparing a jointing ferrule for jointing the formers, sliding the ferrule over the end portions of the formers to be jointed, butting the end faces of the formers against each other in the jointing ferrule, compressing the jointing ferrule to joint the formers such that the compressed ferrule has a diameter equal to that of the former of the superconducting cable, butting the end faces of the superconducting conductors against each other at the outside of the compressed ferrule, and jointing the superconducting conductors with each other such that the jointed superconducting conductors have a diameter equal to that of the superconducting conductor of the superconducting cable. The foregoing steps can decrease the size of the joint.

Joint for superconducting cable

A cable and cable system is provided having a conductor and an insulation layer on an outer circumference of a conductor. The insulation layer is impregnated with a medium-viscosity insulating oil that has a viscosity of 10 centistokes (cst) to less than 500 cst at 60&deg; C. The insulation layer includes an insulating tape that may be one or a combination of composite tape having a polyolefin resin film laminated with a kraft paper on both its sides and an insulating tape including a polyolefin resin film. The cable includes a metal sheath provided on an outer circumference of the insulation layer, and a reinforcing layer formed on an outer circumference of the metal sheath. The reinforcing layer reinforces the metal sheath by absorbing hoop stress exerted on the metal sheath. The cable system includes a submarine-portion cable and a land-portion cable, an oil stop joint box, and an oil feeding tank. The oil stop joint box connects the submarine-portion cable to the land-portion cable, and the oil feeding tank is connected to the land-portion cable which feeds the medium-viscosity insulating oil to the land-portion cable.

Solid cable, manufacturing method thereof, and transmission line therewith

Disclosed is an electrical insulating laminated paper prepared by a process which comprises the steps of melt-extruding a polyolefin resin as a binder onto one or two sheets of a kraft insulating paper by means of a extruder to obtain a laminated paper, and calendering or supercalendering the laminated paper so that the total thickness thereof is from 30 to 200 &mgr;m and the proportion of a polymer comprising the polyolefin resin is from 40 to 90%. The laminated paper is excellent in dielectric properties, dielectric strength, and mechanical properties such as adhesive strength.

Electrical insulating laminated paper, process for producing the same oil-impregnated power cable containing the same

A solid DC cable is made of a conductor having multilayered insulating layer around the outer circumference of the conductor. The insulating layer has a layering configuration selected from one of the following arrangements: (i) a main insulating layer and a low resistance tape layer, where the low-resistance tape layer contains carbon paper that has a volume resistivity which is smaller than that of the main insulating layer; (ii) a main insulating layer containing kraft paper, and a low-resistance insulating layer containing a low resistance kraft paper having a resistivity smaller than the kraft paper of the main insulating layer; (iii) a main insulating layer containing a composite tape, where the tape is contains a laminate of a low-loss plastic film and kraft paper, and a low-resistance insulating layer containing kraft paper having a resistivity lower than the main insulating layer; or (iv) a low-resistance tape layer containing carbon paper described in (i), a low-resistance insulating layer containing the low-resistance kraft paper described in (ii) and a main insulating layer. The low-resistance insulating layer or the low-resistance tape layer is positioned above the conductor in a region where the pressure of the insulating oil becomes negative when a voltage load is cut off.

Solid DC cable

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Osaka, Japan

Hiroshi Takigawa