Hitachi, Ltd.

Isamu Sone

Hiroshi Suzuki

Mikio Sato

Kunio Hirasawa

Akio Nishikawa

Yoshio Yoshioka

Motoo Yamaguchi

Masaru Higaki

Masao Hosokawa

An optical-voltage sensor having a simple structure and being capable of being formed by directly laminating highly sensitive electro-optical elements is disclosed. The optical-voltage sensor includes a light source , a polarizer , a &frac14; wavelength plate , an analyzer , and an O/E converting portion. Two electro-optical elements are arranged adjacent to each other along a light transmitting direction between the &frac14; wavelength plate and analyzer . Transparent electrodes are attached to front and back surfaces of each of the electro-optical elements , and voltages having a magnitude equal to one another and a polarity opposite to one another are applied to the electro-optical elements from a power supply and a power supply , respectively.

Optical-voltage sensor

A SF.sub.6 gas insulating electric apparatus usable as a circuit breaker, etc., containing a SF.sub.6 gas insulator and a resin insulator, both of which insulators are present in an atmosphere to be exposed to arcs, characterized by making at least the surface portion to be exposed to arcs of the resin insulator from a polymer containing nitrogen atoms or a polyolefin resin, and if necessary together with an inorganic filler powder, is excellent in both surface and inner arc resistance and can maintain breaking performance for a long period of time.

SF.sub.6 Gas arc extinguishing electric apparatus and process for

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Hitachi, Japan

Isamu Sone