Hitachi, Ltd.

Minoru Hosoda

Masato Suzuki

Ayumu Morita

Haruo Honda

Shigetoshi Ouchi

Toru Yoshida

Yoshihiko Matsuda

Shigetoshi Oouchi

Yasunobu Fujita

Fumihisa Ichikawa

Keiichi Miyashita

Masaaki Saitou

Akihito Yano

Kouya Yamada

A circuit breaker includes a vacuum valve, an electromagnet including a first coil for driving an operating shaft of the vacuum valve toward an opening direction by electromagnetic repulsion, a movable core and a permanent magnet. Further, an operating mechanism is provided which excites the first coil to close the vacuum valve, holds the vacuum valve closed by an attractive force of the permanent magnet and excites the first coil in a direction reverse to an excitation direction in closing operation to open the vacuum valve. In the circuit breaker, together with the first coil, a second coil is disposed which is excited simultaneously with an electromagnetic repulsion coil for a quick opening operation by electromagnetic repulsion is provided in the electromagnet.

Circuit breaker and opening and closing method thereof

A dc power supply circuit connects a plurality of dc circuit breakers to a semi-conductor converter, returning again to the semi-conductor converter through a dc driving part such as an electric railcar connected to each dc circuit breaker. A second dc circuit breaker of larger capacity than the above-mentioned dc circuit breakers is provided in a return circuit and opened when a short circuit current is detected. A current decreasing means opens the second dc circuit breaker to decrease the short circuit current and includes, for example, a series-circuit of a resistor R and a reactor L. The dc power supply circuit has a large interruption capacity with low resistance loss.

DC power supply circuit

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Hitachinaka, Japan

Minoru Hosoda