| 摘要 |
PROBLEM TO BE SOLVED: To prevent the insulation of a space between a fixed main contact and a moving main contact from being deteriorated by a heated gas flown out from a pressurizing chamber through an insulation nozzle in a gas-blast circuit breaker using a self-expansion method as well as a buffer-style method. SOLUTION: In this gas-blast circuit breaker which has a buffer chamber 7 and a pressurizing chamber 12 and wherein a gas in the pressurizing chamber 12 is spoutad to an arc generated between a fixed arc contact 3 and a moving arc contact 11 through an insulation nozzle 6 when the arc is generated and then, a gas in the buffer chamber 7 is spouted to the arc through the inside of the pressurizing chamber 12 and the inside of the insulation nozzle 6 so that the arc is extinguished, a gas releasing passage 20 for releasing the gas in the buffer chamber 7 toward a fixed main contact 2 when the pressure in the pressurizing chamber 12 is higher than that in the buffer chamber 7 is formed.
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