Hitachi, Ltd.

Hitachi Metals, Ltd.

Kozin Abe

Kenichi Onda

Shin Nakajima

Kazuaki Oishi

Norihira Uozumi

Kohei Yabuno

Noboru Ogawa

A magnetically controlled switching regulator which controls an output voltage using a saturable reactor, wherein the saturable reactor is constituted by a first winding through which an output current flows and a second winding through which a reset current flows. The energy for resetting the saturable reactor is supplied from a capacitor in a smoothing circuit for an output voltage. A turn ratio between the first and second windings is set so that a sufficiently high reset voltage is obtained. Since the reset current of the saturable reactor does not flow through a transformer, the saturation of the transformer and a high increase in temperature thereof do not occur, so that the core of the transformer can be miniaturized and a high gain of the output voltage control circuit can be derived.

Switch mode power supply having magnetically controlled output

In a gas-insulated electric apparatus, such as a gas-insulated switchgear and a gas-insulated bus, having an insulating-gas-filled metallic container or sheath within which an electric conductor carrying a high-voltage current is supported by an insulating supporter, a potential detected by a first potential detector through at least a portion of the insulating supporter and another potential detected as a reference value by a second potential detector through an electro-static capacity disposed between the metallic container and the second potential detector are fed to the inputs of a differential amplifier of a partial discharge detecting device to thereby detect possible partial discharges along the insulating supporter with high sensitivity.

Gas-insulated electric apparatus and method of detecting partial

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Hitachi, Japan

Kozin Abe