Hitachi, Ltd.

Atsuji Watanabe

Shinji Seto

Hideo Kawamoto

Masanori Tsukushi

Youichi Ohshita

Yasuhide Takeda

Daisuke Ebisawa

Masatomo Ohno

Shunji Tokuyama

Masayuki Uchiyama

In a hydraulic pressure actuating apparatus for a circuit breaker, contacts of the circuit breaker have a moving contact and a stationary contact for turning on/off current. A shaft, at an end portion of which is attached the moving contact, and at the other end of which is attached a piston, is received within a cylinder. A directional control valve exchanges oil pressure for actuating the piston. For changing over the directional control valve, pilot valves are provided. Each pilot valve has a pair of valve bodies, each opposing to each other, and springs. One of the valve bodies is able to stroke up to contact with the valve body of the other valve body, therefore giving no ill influences upon actuating time, even if drawback occurs in the pilot valves in the hydraulic pressure actuating apparatus for the circuit breaker.

Hydraulic pressure actuating apparatus for circuit breaker

A first puffer chamber is formed by a puffer cylinder having a substantially cylindrical flange portion and a shaft portion, and a fixedly disposed piston. The piston is formed in a cylindrical shape sealed with respect to an external space, and is constituted to be accommodated in the flange portion of the puffer cylinder at the circuit breaking position of the circuit breaking unit. The internal space of the piston is constituted as a second puffer chamber which is designed to communicate with the first puffer chamber. The gas accumulated in the second puffer chamber is continuously blown out toward between the electrodes, thereby prolonging an effective interruptable arc time span without increasing the size of the circuit interrupting unit and operating unit.

Grounding switch gear device

Growing community of inventors

Tokyo, Japan

Atsuji Watanabe