Hitachi, Ltd.

Katsuji Shindo

Jun Ozawa

Kazuya Ooishi

Yoshitaka Yagihashi

Shingo Shirakawa

Tokio Yamagiwa

Fumihiro Endo

Toshiaki Rokunohe

Seizo Nakano

Takeo Yamazaki

Satoshi Watahiki

Takahide Matsuo

Goro Suzuki

Seiichi Maruyama

Akio Mizukoshi

Yoshi Akatsu

Takeuchi Shigetaka

A bushing has a central conductor, and a plurality of internal shield rings. Gaps are formed between the shield rings such that equipotential lines extend through gaps. Electric field concentration in a tangential distribution on a part of the surface of the bushing corresponding to an upper part of an internal shield ring is relieved to prevent corona discharge under wet conditions, and antipollution performance and withstand voltage characteristics can be improved.

Bushing

A substation includes standard arresters installed near a bushing of a power transmission line entrance and at a connecting bus of a transformer and one or more high voltage arresters having a discharge voltage 10 to 30% higher than a standard arrester. Each high voltage arrester uses zinc oxide elements and is disposed on a line side of a line entrance breaker and/or near an open end of a double main bus in the substation.

Substation with surge arresters

In order to provide an arrestor for a gas insulated switchgear in which the voltage share rates of respective zinc oxide non-linear resistance elements are made uniform, in an arrestor constituted by a plurality of columns for a gas insulated switchgear, the thickness or the capacitance of insulator spacers contacting the high voltage terminal or the ground terminal in respective columns is controlled, whereby the potentials of the zinc oxide non-linear resistance elements close to the high voltage terminal or to the ground terminal in the respective columns are shifted close to the potentials of the high voltage terminal or the ground terminal.

Arrestor for gas insulated switchgear

An arrester for a gas insulated switchgear device includes a closed container filled with an insulating gas; a columnar piled body formed by piling up a plurality of zinc oxide resistance elements between a high voltage side terminal and a grounding side terminal disposed in the closed container; a plurality of potential equalizing rings electrically and mechanically connected to the high voltage side terminal of the columnar piled body, the potential equalizing rings being disposed in a discrete manner along the piling up direction of the zinc oxide resistance elements with a predetermined spacing distance while surrounding the outer circumference of the columnar piled body; and an intermediate electrode disposed around the columnar piled body at a position facing the potential equalizing ring located nearest to the grounding side terminal among the potential equalizing rings.

Arrester for gas insulated switchgear device

A zinc oxide type arrester including: four constitutional units electrically connected in parallel and a closed container accommodating the constitutional units. Each of the constitutional units includes a first columnar stack body composed by stacking zinc oxide elements and insulating spacers in a first predetermined order, a second columnar stack body composed by stacking zinc oxide elements and insulating spacers in a second predetermined order and a third columnar stack body composed by stacking zinc oxide elements and insulating spacers in a third predetermined order, the zinc oxide elements in the first, second and third columnar stack bodies contained in one constitutional unit are connected in series as a whole, and at least two of the three columnar stack bodies having same stacking structures in adjoining constitutional units are arranged to closely face each other.

Zinc oxide type arrester

A grounding tank type arrester comprises a plurality of columns sorted into current folding columns and current pass columns. Each current folding column includes a plurality of stack sets of an element unit, having a plurality of zinc oxide elements, and an insulating spacer and the plural stack sets are stacked in regular sequence so that one element unit and one insulating spacer are stacked alternately. Each current pass column includes a plurality of stack sets of a zinc oxide element and an insulating spacer and the plural stack sets are stacked in regular sequence so that one zinc oxide element and one insulating spacer are stacked alternately. Individual zinc oxide elements on one level of individual current folding columns and individual zinc oxide elements on the one level of individual current pass columns are interconnected together by bridge conductor plates. The direction of current flowing through bridge conductor plates for connecting together zinc oxide elements on the one level of the current folding columns and current pass columns is inverse to the direction of current flowing through bridge conductor plates for connecting together zinc oxide elements on the neighboring level of the current folding columns and current pass columns and hence the residual inductance of the arrester can be reduced.

Grounding tank type arrester

In an enclosed-type zinc-oxide surge arrester with a grounded tank filled with an insulating medium, and a non-linear resistor assemblage which is connected at one end to a high voltage conductor and at the other end to the ground potential portion within the grounded tank, two or more ring-like shield means such as shield rings are disposed on the high voltage conductor side of the non-linear resistor assemblage at given distances. The use of the ring-like shield means makes more uniform the voltages shared by the respective non-linear resistors. The ring-like shield means may be formed with the configuration and diameter, and the number of them used being properly selected.

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Hitachi, Japan

Katsuji Shindo