Hitachi, Ltd.

Shikoku Electric Power Co., Inc.

The Tokyo Electric Power Company, Incorporated

Etsunori Mori

Katuo Sugawara

Hideo Tsukioka

Shigeo Shiono

Masaru Higaki

Atsushi Miki

Seiichi Sakai

Minoru Hoshi

Ictitaro Tani

Toshihiko Gange

Tadashi Sato

Kiyoshi Kurosawa

Sadamu Saito

Etsuo Ohe

Masaru Watanabe

Yoshitake Kashima

Ichitaro Tani

Kazuyuki Seino

Genji Takahashi

Tadashi Kiuchi

Kiyoto Hiraishi

Yoshinori Shirai

Fumio Nishikawa

An optical d.c. voltage transformer having an electrooptic medium to which a d.c. electrical field or voltage to be measured is to be applied. The electrooptic medium affects the polarized light from the polarizer by an electrooptical effect to a degree proportional to the strength of the electrical field or voltage. The transformer includes a photodetector for producing an optical signal proportional to the affected light received from the electrooptic medium, a device for converting the optical signal from the photodetector into an electrical signal, a chopper for pulsating the electrical field or voltage to be applied to the electrooptic medium, in terms of time, a detector for demodulating the electrical signal from the converting device in synchronism with the pulsated electrical field or voltage, and an output unit for visually presenting the demodulated electrical signal similar in polarity to the electrical field or voltage to be measured.

Optical d.c. voltage transformer

A gas-insulated stationary induction electrical apparatus comprising a first closed vessel sealingly accommodating therein a main body having an iron core formed by laminating silicon steel sheets and also having at least one set of windings each consisting of a high-voltage winding and a low-voltage winding which are disposed apart from the iron core on both sides thereof, and a liquid medium for effecting cooling and insulation; a second closed vessel formed of an insulating material and sealingly accommodating therein the first closed vessel; and an insulating gas under a predetermined pressure which is sealed within the gap between the first and second vessels, wherein the induction apparatus main body is submerged in the liquid medium.

Gas-insulated stationary induction electrical apparatus

A winding for a static induction apparatus such as a transformer, a reactor and the like comprises a plurality of interleaved coils each formed by winding an electrically insulated strand conductor in a radial spiral. The coils are stacked axially and electrically connected in series between a line terminal and another terminal such as a neutral terminal. The winding is divided into a plurality of blocks each including a plurality of ones of the interleaved coils. The number of turns of each coil belonging to the block on the other terminal side is decreased as compared with that of each coil belonging to the block located closer to the line terminal, to thereby reduce the series electrostatic capacitance of the coils stepwise from one to another block starting from the one located on the line terminal side. The distribution constant is thus decreased. Favorable surge withstanding characteristics are attained, reliable insulation is assured and the winding can be realized in a reduced size.

Winding for static induction apparatus

Method and apparatus for diagnosing abnormality of an oil-filled electric apparatus is disclosed. Presence or absence of abnormality is determined by comparing contents of plural predetermined components contained in gas extracted from the oil of the electric apparatus with respective predetermined reference values. The type of abnormality is determined on the basis of at least one set of two specific components selected from the plural components.

Method and apparatus for diagnosing oil-filled electric apparatus

A gas chromatographic apparatus having at least two gas separation columns arranged in parallel to each other, the outlet of the first gas separation column being connected to a gas sensor through a column switch valve, and the outlet of the second gas separation column being connected to the column switch valve through a gas detection time-controlling pipe, where when the first gas separation column is communicated with the gas sensor, the outlet of the second gas separation column is made open to the atmosphere by the column switch valve, or when the second gas separation column is communicated with the gas sensor, the outlet of the first gas separation column is made open to the atmosphere by the column switch valve, or the apparatus having a first gas separation column whose inlet is connected to the switch valve and at least two second columns whose inlets are connected to the outlet of the first gas separation column, whose outlets are connected to the gas sensor and which are arranged in parallel to each other through the column switch valve, where the first gas separation column, one of the second columns and the column switch valve are communicated with each other, by the column switch valve. A chromatogram with distinctly separated peaks in a continued state can be obtained in a short time by only one detecting and recording means.

Gas chromatographic apparatus

In an apparatus for detecting gas components in the oil in an oil-filled device, which comprises a gas-storing chamber being provided at an oil-filled device containing an insulating oil through a gas-permeating material capable of separating gas components from the insulating oil, a gas calibration tube being provided at the gas-storing chamber through a switch valve, and a gas chromatographic device connected to the gas calibration tube through the switch valve, any influence of gas components in a subatmospheric pressure is eliminated and exact concentrations of gas components are detected by providing at least one stirring mixer having at least one throttle perforation in a carrier gas passage for supplying the gas components from the gas calibration tube to the gas chromatographic device at the upstream side of a gas separation column of the gas chromatographic device, or by proving a circulation passage between the gas-storing chamber and the gas calibration tube, a valve capable of being exposed to the atmosphere at the circulation passage, and a gas circulation unit at the circulation passage for circulating the gas in the circulation passage.

Method and apparatus for detecting gas components in oil in oil-filled

A multi-layer winding comprising cylindrically-wound conductors and having different diameters are arranged concentrically. The layer windings are connected in series from inside to outside. Each layer winding has a layer insulator arranged on the inside thereof with a flange. Inwardly of the layer insulator and adjacent to the next inward layer winding is formed an oil gap functioning as a cooling-oil path. That oil-gap-equivalent part at and in the vicinity of the ends of the layer winding where the potential is maximum between adjacent layer windings is larger than the other parts thereof. This construction reduces the intensity of the electric field at the ends of each layer winding and eliminates partial discharge, thus improving the reliability and rendering the multi-layer winding compact and light in weight as a whole.

Cylindrical winding for induction electrical apparatus

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Hitachi, Japan

Etsunori Mori