Hitachi Cable, Inc.

Moritada Marumo

Hideki Yagyu

Kiyoshi Watanabe

Kazuo Kotani

Kenichiro Soma

Chuki Ikeda

Yukio Shimazaki

Toshio Shiina

Katsutoshi Hanawa

Nobuju Takaoka

A power cable such as a rubber or plastic insulated power cable is diagnosed to be detected an insulation deterioration resulted from water tree generated in an insulation material thereof. At first, charging current flowing from the power cable through a grounding conductor connected to a metal shielding layer thereof to the ground is measured under a state that a rated AC voltage is applied to the power cable. In accordance with the charging current, stray current flowing from the ground to the power cable is calculated. Then, a direct current component of the charging current is detected, and an intrinsic direct current component is calculated by subtracting the stray current from the direct current component. The insulation deterioration is diagnosed in accordance with the level of the intrinsic direct current component.

Method for diagnosing an insulation deterioration of a power cable

A semiconductive resin composition comprising 100 parts by weight of a polymer component comprising an ethylene-based copolymer, an ethylene-propylene rubber, and a low molecular weight polyethylene having an average molecular weight of 1,000 to 4,000 and 40 parts by weight or more of electroconductive carbon black.

Semiconductor resin composition

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Ibaraki, Japan

Moritada Marumo