Hitachi, Ltd.

Hideaki Tsuda

Kiyoji Iwashita

Yukio Kurosawa

Keiichi Kuniya

Ryuji Watanabe

Haruo Honda

Sadami Tomita

Akira Wada

Shigetoshi Ouchi

Toru Yoshida

Tutomu Kanno

Yukio Kugoh

Fumihisa Ichikawa

Takashi Ichinose

A commutating type DC circuit breaker arrangement comprising: a vacuum circuit breaker having a movable electrode and stationary electrode; a series circuit of a capacitor, a saturation reactor and a commutating switch which is connected in parallel with the vacuum circuit breaker; and an electrical relay for detecting a predetermined electrode open position at which a sufficient insulating distance between the movable electrode and the stationary electrode is maintained via movement of a predetermined position on an actuating rod for the movable electrode and for closing the commutating switch in response to the detection of the predetermined electrode open position.

Commutating type DC circuit breaker arrangement

A vacuum circuit breaker comprising a vacuum vessel and a pair of electrodes disposed in the vessel, which is superior in chopping current characteristic, at least a contact of at least one of the electrodes being made of a member having a skeleton of an iron group element, pores in which skeleton are impregnated with at least one kind selected from a group consisting of silver; an alloy of Ag and at least one of Te, Se, Bi, Pb, Tl, In, Cd, Sn and Sb; and the intermetallic compound of Ag, the breaker having rated voltage of 3.6 to 36 KV and rated breaking currents of 8 to 60 KA.

Vacuum circuit breaker

A vacuum interrupter comprises a vacuum vessel, at least a pair of electrical conductor rods extending from interior to exterior of the vacuum vessel, and at least a pair of separable composite electrodes respectively connected to the tip of the electrical conductor rods. Each of the composite electrodes has a main electrode, a parallel magnetic field generator for generating a parallel magnetic field which acts on an arc created when one main electrode is separated from the other, and a magnetic field suppressor of high electrical conductivity embedded in a central portion of the main electrode for partly cancelling the parallel magnetic field. In the vacuum interrupter, when the parallel magnetic field permeates through the magnetic field suppressor, eddy current flow is caused therein. A magnetic field due to the eddy current has a polarity opposite to that of the parallel magentic field and partly cancels the parallel magnetic field. Intensity of the parallel magnetic field then becomes smaller at the central portion than that at the other peripheral portion, and the arc tends to shift from the magnetic field suppressor to the outer peripheral portion, thereby preventing fusion damage of the magnetic field suppressor.

Vacuum interrupter

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Hitachi, Japan

Hideaki Tsuda