Hitachi, Ltd.

Isao Nishida

Yukio Kurosawa

Youichi Ohshita

Osamu Koyanagi

Takeshi Takahashi

Koji Sasaki

Tokio Yamagiwa

Masanori Tsukushi

Seizo Nakano

Akira Hashimoto

Tuneo Kishi

Yoshihito Asai

Kazuhiro Saito

Hirohiko Yatsuzuka

Shigetaka Takeuchi

Masaru Watanabe

Kastuichi Kashimura

Minori Sato

Katuichi Kashimura

Takashi Minakawa

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 circuit breaker with a parallel resistor which fulfills with a simple structure incompatible requirements for a resistance circuit making contact with regard to maintenance of the dielectric strength and prearcing characteristic between electrodes. A resistance circuit making contact 2 and a resistance circuit breaking contact 3 are electrically connected in parallel, one end of the parallel circuit is connected to one end of a common resistor and the other end of the parallel circuit and the other end of the resistor are connected to the respective ends of a main contact 1. After the opening of the resistance circuit making contact 2 the resistance circuit breaking contact 3 is still closed.

Circuit breaker with parallel resistor

A three-phase common tank type gas circuit breaker has a grounded tank filled with an insulating gas and accommodating three interrupter assemblies for three phases of the electric power. Each assembly includes a parallel electrical connection of an interrupter having stationary and movable contacts, a capacitor and a closing resistor. The interrupters for the three phases are disposed in spaced relationship circumferentially of the tank and have axes extending axially of the tank. The closing resistor for each phase is disposed on one side of the associated interrupter adjacent an adjacent interrupter for a different phase, while the capacitor for each phase is disposed on the inner or outer side of the associated interrupter, whereby the radial and axial dimensions of the grounded tank can be reduced.

Gas circuit breaker

In a circuit breaker in which an interrupting device, a resistor device and a capacitor device are connected in parallel, a shield device is arranged to shield the interrupting device and the resistor device and comprises a first shield for shielding the stationary main contact and stationary resistor contact and a second shield for shielding the movable main contact and movable resistor contact. Each of the first shield and the second shield comprises a large shield portion and a small shield portion, and the small shield portions are arranged between the large shield portions. The small shield portion terminates in the vicinity of the top of the main contact and of the top of the resistor contact. The small shield portion comprises wide portions situated substantially in the direction of an axis joining centers of the main contact and resistor contact and narrow portions situated substantially in the direction perpendicular to the axis. The width of the narrow portions is smaller than the width of the wide portions, and at least a part of the capacitor device is arranged over the narrow portions. In the circuit breaker, since the capacitor device is arranged over the narrow portions, the space for arranging the capacitor device is larger than the conventional circuit breaker, the arrangement of the isoelectric liens is not disturbed or disordered locally in the vicinity of the top of the shield of the stationary main contact and in the vicinity of the movable main contact and high dielectric strength between the main contacts is obtained.

Circuit breaker

A plurality of breaking portions forming a vertically-disposed circuit breaker are connected in series and open and close the circuit within a gas-tight sealed enclosure. The enclosure is provided at its both sides with openings for connection of one and the other ends of the breaking portions, to which openings main bus bars and an insulated-led-out device are connected, respectively. The breaking portions each have a fixed contactor and a movable contactor, and the movable contactor is put into contact with or is separated from the fixed contactor by moving the movable contactor upward or downward under control of an operating device.

Gas-insulated switchgear equipment

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Hitachi, Japan

Isao Nishida