Hitachi, Ltd.

Masaru Watanabe

Yukio Kurosawa

Tokio Yamagiwa

Youichi Ohshita

Etsunori Mori

Yoshihito Asai

Isao Nishida

Minoru Hoshi

Shigeo Kikuchi

Tadashi Kiuchi

Kiyoto Hiraishi

An electrical power supply system includes an electrical power source system connected to a bus bar and a plurality of electric power transmission systems each connected via circuit breakers to the bus bar. The supply system has overvoltage suppression equipments each installed between the transmission system and the ground. The overvoltage suppression equipment includes a switching device and an impedance connected to the switching device. The switching device in a sound transmission system is closed when the circuit breaker operates in other faulty transmission system, thereby an overvoltage being occurred on the sound system is effectively suppressed.

Electrical power supply system

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

An on-load tap-changing transformer in which its high-voltage winding is axially divided into parallel-connected halves, and an end conductor constituting part of the high-voltage winding is connected to the other terminal of each of the halves. A coarse tap coil connected by the end conductor to the other terminal of each of the halves of the high-voltage winding is disposed adjacent to the associated half, and a fine tap coil connected to the coarse tap coil through a coarse tap selector used for the change-over of the tap position to the taps of the coarse tap coil is disposed at a radial position spaced apart from the coarse tap coil. The end conductor is wound together with the conductors of the fine tap coil.

On-load tap-changing transformer

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Hitachi, Japan

Masaru Watanabe