Hitachi, Ltd.

Hideyuki Kotsuji

Makoto Hirose

Makoto Koizumi

Hajime Urai

Jun Nukaga

Takahiro Nishimura

An object is to enhance direct-current insulating performance of a gas-blast circuit breaker. The gas-blast circuit breaker includes: a pair of main contacts disposed in a gas tank to face each other and configured to operate for opening and closing a circuit; a pair of arc contacts disposed to face each other and configured to operate for opening and closing the circuit, the arc contacts being disposed coaxially with the main contacts at locations close to the centers of the main contacts, respectively; and an elastic electrically conductive material disposed on an outer surface of an insulating nozzle facing an inner surface of one of the main contacts.

Gas-blast circuit breaker

A pair of arcing contactsandfacing each other are placed in a tankto perform opening and closing operation, and a puffer cylinderis coaxially provided on the circumference of one arcing contact. A puffer chamberis comprised of the puffer cylinder, a fixed piston, and a hollow rod. An insulating nozzleforming a space communicating with the puffer chamberis provided. An exhaust tubefor exhausting and cooling hot gas discharged from an arc produced in the insulating nozzleis provided on the circumference of the other arcing contact. A structurefor temporarily reducing the flow path area is provided on the inner circumferential surface at short of the end portion of the exhaust tube

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Tokyo, Japan

Hideyuki Kotsuji