Mitsubishi Electric Corporation

Mitsubishi Denki Kabushiki Kaisha

Eiichi Nagao

Satoru Toyama

Tsuyoshi Amimoto

Fukutaro Kato

Kota Mizuno

Junji Tanimura

Noboru Hosokawa

Hiroyuki Hama

Hitoshi Sadakuni

Takuya Otsuka

Kiyoshi Inami

Kozo Tachibana

Kentaro Taninouchi

Kenichi Mori

Shiro Yamauchi

Hirotaka Muto

Kyoichi Ohtsuka

Takanori Sone

Tadao Minagawa

Koichi Hirooka

Makiko Kawada

Ei Tsuchie

Yoshio Kimura

The present invention is a method for preventing copper sulfide generation in oil-filled electrical equipment having an inhibitor of copper sulfide generation in insulating oil, and the method is characterized in monitoring characteristics of the insulating oil and performing re-addition of the inhibitor at an appropriate moment in accordance with a result of the monitoring.

Method for suppressing copper sulfide generation in oil-filled electrical equipment

The present invention relates to an electric insulating oil inspection method for determining whether or not an inhibitor-consuming substance is present in an electric insulating oil. The inhibitor-consuming substance is such a substance that causes to decrease over time a concentration of an inhibitor which is added to the electric insulating oil to inhibit copper sulfide from being generated on an insulating paper immersed in the electric insulating oil. The electric insulting oil inspection method includes steps of: preserving the electric insulating oil at a predetermined condition, measuring a concentration of the inhibitor, and determining that the inhibitor-consuming substance is present upon condition that a decrement of the concentration of the inhibitor relative to an initial concentration of the inhibitor becomes not less than a specified amount within a predetermined period.

Electric insulating oil inspection method, electric insulating oil treatment method, and oil-filled electric device maintenance method

An object of the invention is to provide a diagnostic method for an oil-filled electrical device that considers a temperature distribution in the oil-filled electrical device and enables accurate diagnosis to be conducted even when the method is applied to diagnosis of an actually operating device, and further provide a method with which such diagnosis of an oil-filled electrical device can be conducted from a component analysis value of an insulating oil in the oil-filled electrical device. The invention is a diagnostic method for an oil-filled electrical device including in an insulating oil a metal part wrapped with insulating paper, and determines that a time when a surface resistivity of a maximum precipitation site where metal sulfide is most precipitated on the insulating paper reaches a preset surface resistivity management value is a time of occurrence of an abnormality.

Diagnostic method for oil-filled electrical device, diagnostic device for implementing the diagnostic method, and oil-filled electrical device provided with the diagnostic device

The present invention provides a method for inhibiting production of copper sulfide in an electrical insulating oil inside an oil-filled electrical apparatus, including adding a benzotriazole compound not having a long-chain alkyl group when the oil-filled electrical apparatus is an open-type oil-filled electrical apparatus, or adding a benzotriazole compound having a long-chain alkyl group when the oil-filled electrical apparatus is a closed-type oil-filled electrical apparatus.

Method for inhibiting generation of copper sulfide

An initial concentration of the residual concentration of a causative substance contained in an insulating oil is compared with a reference value. The causative substance reacts with a conductor forming a winding of an oil-filled electrical device to generate an electrically conductive compound. The reference value is defined as a value for determining whether a main determinant that determines the lifetime of the oil-filled electrical device is generation of the electrically conductive compound or degradation of insulating paper. Based on the initial concentration of the causative substance and the reference value, the lifetime of the oil-filled electrical device is assessed.

Lifetime assessment apparatus and method for oil-filled electrical device, and degradation suppression apparatus and method for oil-filled electrical device

In a gas insulated breaking device which accommodates open/close elements including a puffer cylinder which compresses an insulation gas and extinguishes an arc and a contact finger which has a slide contact portion which is brought into slide contact with a slide contact portion of the puffer cylinder in the inside of a vessel in which the insulation gas is sealed, a relatively soft plating film is formed on the slide contact portion of the puffer cylinder, and a relatively hard plating film is formed on the slide contact portion of the contact finger, and the silver plating film of each slide contact portion has an inner layer thereof formed of a soft film and an outer layer thereof which constitutes a surface portion formed of a hard film.

Gas insulated breaking device

An oil immersed electrical apparatus such as an oil immersed transformer that can detect copper sulfide precipitated on coil insulating paper is provided. In the oil immersed transformer in which a coil with its surface covered by insulating paper is arranged in a container filled with insulating oil, a detection member is prepared by providing two electrodes on a surface of a plate-like pressboard formed of cellulose, which is a same material as that of the insulating paper, this detection member is arranged in contact with the insulating oil, and generation of copper sulfide is detected from reduction in a surface resistance between the electrodes. The temperature of the detection member is set higher than the temperature of the coil so that copper sulfide is generated thereon prior to generation of copper sulfide on a coil unit.

Oil immersed electrical apparatus

A gas-insulated equipment such as a gas-insulated switchgear provided according to the invention can efficiently improve dielectric strength of an entire electrode system considering electric field distribution of the electrodes and conductors and improving insulation coordination so that miniaturization of the entire device can be achieved. The gas-insulated switchgear includes insulating gas sealed within an earth metal container and an insulating spacer insulating and supporting high-voltage receiving portions. Surfaces of shielding electrodes having a larger diameter than that of high-voltage conductors are covered with thick dielectric coatings, and surfaces of the high-voltage conductors are covered with thin dielectric coatings.

Gas-insulated equipment

Dehumidifier and method of using

Growing community of inventors

Chiyoda-ku, Japan

Eiichi Nagao