Hitachi, Ltd.

Yoshihito Asai

Yukio Kurosawa

Osamu Koyanagi

Eisaku Mizufune

Goro Daimon

Katsuichi Kashimura

Kogi Ishikawa

Kenji Tsuchiya

Koji Sasaki

Tokio Yamagiwa

Takashi Sato

Masanori Tsukushi

Youichi Ohshita

Makoto Yano

Kenichi Natsui

Isao Nishida

Masaru Watanabe

Kastuichi Kashimura

Ken'ichi Natsui

Yukio Korosawa

The steep initial rate of rise of the transient recovery voltage across the poles of a circuit breaker just after a fault current break is decreased. The breaking performance in the case of a short-circuit fault to ground taking place in an electrical power transmission system at relatively as near a place as several kilometers apart from the circuit breaker, that is a short-line-fault is improved by a saturable reactor having a capacitor connected in parallel therewith to the circuit breaker in series. As a result, as the saturable reactor changes from the magnetically saturated state to the unsaturated state just before the zero point of the fault current, the self-inductance of the saturable reactor gradually increases and an LC resonance is produced between the self-inductance of the saturable reactor and the capacitor connected to the saturable reactor in parallel. Therefore, the peak value and the time period of the current flowing from the saturable reactor can be controlled to control the initial rate of rise of the transient recovery voltage.

Method of controlling transient recovery voltage and gas insulation

A puffer type gas-blast circuit breaker includes a guide section arranged at a coupler section between a shaft section of a puffer cylinder and a dielectric operating rod, for guiding both in the axis direction of a current interruption section and in the radial direction thereof, thereby to suppress or eliminate the occurrence of misalignment of center axis between movable components and fixed ones thus causing a gap to remain constant between a dielectric nozzle and a fixed arc contact. With such an arrangement, the gap between the nozzle and the contact can be kept uniform even when the pole-to-pole distance is increased with an increase in the high withstanding voltage of the breaker. This ensures that the surface-creeping electric field on the inner surface of the dielectric nozzle can be at a desired design value, thus enabling to provide a stable pole-to-pole insulation characteristic during current interruption operations.

Puffer type gas circuit breaker

A puffer type gas breaker is provided, in which high-temperature gas, heated by an electric arc produced immediately after a large current is broken, is quickly discharged to enhance inter-pole dielectric performance. A fixing portion for fixing an arc contact is provided in a cylindrical exhaust pipe for exhausting the high-temperature gas heated by an electric arc produced between poles immediately after a large current is broken. A rectifying member or members is provided in the fixing portion of the cylindrical exhaust pipe. An exhaust port or ports is formed in the fixing portion of the cylindrical exhaust pipe, and a shield is disposed around the outer periphery of the exhaust port or ports.

Puffer type gas breaker

A compression gas puffer type circuit breaker has a magnetic body surrounding a conductor between a stationary arc contact and a main bus conductor. The magnetic body is protected from being exposed to heated puffer gas generated when a movable arc contact is separated from the stationary arc contact by disposing an insulator partition plate supporting the conductor at the downstream end of a cylindrical contact base carrying a main stationary contact and upstream of the magnetic body. Conductors are disposed around the magnetic body so as to increase flux linkage with the magnetic body when an arcing current flows through the conductor during a circuit breaking operation.

Compression gas puffer type circuit breaker

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 tank type gas circuit breaker for a three-phase alternating current, comprises: three hollow members spaced in parallel with each other; a single stationary side end plate air-tightly fixed to first ends of the three hollow members; a single mechanism side end plate fixed to second ends of the three hollow members; three stationary contacts each supported to the stationary side end plate and extending in the three hollow members; three movable contacts each supported to the mechanism side end plate and extending in the three hollow members; insulated rods extending in the three hollow members while passing through the mechanism side end plate for interrupting contacts between the movable contacts and the stationary contacts; an operational rotary shaft mechanism disposed adjacent to the mechanism side end plate and connected to the insulated rods for driving each of the insulated rods; an actuator for driving the operational rotary shaft mechanism; two bushing porcelain insulators located on a top surface of each of the hollow members; current transformers arranged in lower sides of the bushing porcelain insulators; conductors disposed within the bushing porcelain insulators and connected to the movable and stationary contacts, and arc-extinction gas filled in the hollow members.

Tank type gas circuit breaker

A puffer type gas circuit breaker in which a stationary arcing contact constituting the stationary part of a breaking unit is surrounded by an envelope including an annular shield element acting to relieve the electric field around the free end of the stationary arcing contact, and a gas passage extending in the axial direction of the stationary arcing contact is formed in the side portion of the envelope so that the greater portion of an arc extinguishing gas puffed toward the stationary arcing contact can be discharged through the gas passage. In the circuit breaker, a gas-shielding hood is disposed around the envelope for preventing the gas stream discharged from the gas passage from flowing directly straight.

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Hitachi, Japan

Yoshihito Asai