Hitachi, Ltd.

Minori Satoh

Yukio Kurosawa

Kunio Hirasawa

Tokio Yamagiwa

Fumihiro Endo

Masanori Tsukushi

Isao Takahashi

Akira Hashimoto

Kastuichi Kashimura

A gas blast circuit breaker comprises an insulation nozzle for blowing extinguishing gas to an arc generated between a stationary contact and a movable contact. The nozzle has a throat section into and out of which one of the two contacts is movable and a divergent section provided downstream of the throat section. A slanting surface for increasing a reflectivity of energy intensity of the arc is formed on the divergent section of the nozzle. The nozzle is formed of a fluoroplastic material and boron nitride powder of not more than 15 vol. % is added as a filler.

Gas blast, puffer type circuit breaker with improved nozzle

The invention relates to a synthetic equivalent test circuit which can generate a 4-parameter transient recovery voltage TRV, for verifying a large current breaking performance of a power circuit breaker. A current source current is supplied to only a testing circuit breaker which is to be tested and an auxiliary circuit breaker. A small current with respect to the current source current is transmitted to the first and second auxiliary switches from a power source. When the small current form the current source or the resonance circuit flows, the first auxiliary switch is opened almost simultaneously with the auxiliary circuit breaker, the testing circuit breaker and operates so as to break the current at the time point of the final zero point of the current source current. Therefore, the connection of the voltage source circuit just before the final zero point of the current source current, that is, the current supply of the voltage source current and the breaking of a capacitor circuit current by the first auxiliary switch generates a 4-parameter TRV that can be accomplished easily.

Synthetic equivalent test circuit of circuit breaker

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Hitachi, Japan

Minori Satoh