Finnegan, Henderson, Farabow, Garrett & Dunner L.L.P.
Gas circuit breaker
A gas circuit breaker 1 includes an insulation nozzle 23 that guides arc-extinguishing gas to an arc between a first arc contactor 21 and a second arc contactor 41 when a trigger electrode 31 becomes an opened state relative to the first arc contactor 21. The second arc contactor 41 has an opening 41a for spraying the arc-extinguishing gas, and the opening 41a is closed by the trigger electrode 31 in the first half of a current breaking action, and is opened by separation of the trigger electrode in the latter half of the current breaking action. An opening area of a first exhaust port 41b formed between the second arc contactor 41 and the insulation nozzle 23 for exhausting the arc-extinguishing gas is 0.2 times or more and two times or less of an opening area of the opening 41a of the second arc contactor 41. 
KABUSHIKI KAISHA TOSHIBA TOSHIBA ENERGY SYSTEMS & SOLUTIONS CORPORATION
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Toshiyuki Takanori Tomoyuki Tsutomu Norimitsu
Uchii Iijima Yoshino Tanaka Kato