Hitachi, Ltd.

Kiyoji Iwashita

Yukio Kurosawa

Ryuji Watanabe

Akira Wada

Hiroshi Inoue

Junzo Kawakami

Minoru Kanoi

Hiroyuki Kudo

Kazuo Nishijima

Toru Takei

Yuzuru Imamura

Hideaki Tsuda

Saburou Yasukawa

Hiroyuki Sugawara

Keiichi Kuniya

Nobuo Abe

Hisashi Ando

Hisashi Andoh

Sadami Tomita

Seiki Shimizu

Morihisa Matumoto

Takanao Kurasawa

Syunkichi Endo

Kinko Shimizu

An electrical power distribution monitoring system is provided for a power distribution line having a plurality of sections with a plurality of electrical loads connected to the power distribution line to form a power distribution network. The monitoring system has at least one sensor for at least one present electrical value at least one point of the network, and estimates electrical values for at least one section of the line in dependence on both of present electrical values measured by the sensor and data relating to past power consumption by loads connected to the line. Improved prediction of actual conditions in the distribution line can be obtained.

Electrical power distribution monitoring system and method

An electrical power distribution monitoring system is provided for a power distribution line having a plurality of sections with a plurality of electrical loads connected to the power distribution line to form a power distribution network. The monitoring system has at least one sensor for at least one present electrical value at at least one point of the network, and estimates electrical values for at least one section of the line in dependence on both of present electrical values measured by the sensor and data relating to past power consumption by loads connected to the line. Improved prediction of actual conditions in the distribution line can be obtained.

A production method of a vacuum circuit breaker electrode comprises the steps of mixing conductive metal powder, and refractory material powder with a higher melting point than said conductive metal powder, compacting the resultant mixture to form a compact, presintering the compact in a atmosphere of high purity hydrogen, sealing a presintered body in a capsule while exhausting, heating and degassing, and subjecting the sealed capsule to hot isostatic pressing treatment. The conductive metal powder is one or both of Cu and Ag. The hot isostatic pressing treatment is effected at a temperature higher than a melting point of the conductive metal so that the presintered body is sintered under liquid phase, and a part of molten conductive metal component is seeped out on a sintered body surface.

Method for making vacuum circuit breaker electrodes

A cylindrical coil electrode incorporated in a vacuum interrupter comprises a cylindrical body having an opening at one end thereof, two electrical connections provided between the edge surface of the opening of the cylindrical body and a main electrode, two arcuate slits formed on the cylindrical body between the two electrical connections, two arcuate current paths formed in the cylindrical body by the arcuate slits beginning as a respective electrical connection and ending at a rod, and two current blocking slits formed on the cylindrical body at positions where one end of each of the current paths laps the other end of the other current paths. Because of the above structure, one-turn current flows throughout the current paths so that a uniform axial magnetic field can be applied to the main electrode, and an arc current can be uniformly distributed over the entire surface of the main electrode, thereby improving the current interruption performance of the vacuum interrupter.

Vacuum interrupter

A pair of separable disc shaped electrodes for a vacuum circuit breaker, each including an annular contact part formed around the outer circumferential portion of the electrode on the facing surface to the other electrode, a round recessed part formed on the inner portion thereof and surrounded by the annular contact part, an elastic support plate placed on the non-facing surface thereof and three straight grooves extending from the outer periphery of the annular contact part to the inner periphery thereof so that arcing on the round recessed part is prevented during a circuit breaking operation of the vacuum circuit breaker.

Vacuum circuit breaker

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.

Disclosed is a vacuum switch having a container and a pair of contact electrodes, and a method of manufacturing the same, in which at least one of the contact electrodes is constituted by a member made up of a skeleton containing cobalt as its principal component with pores into which a copper alloy containing copper as its principal component, silver, and a low melting point and high vapor pressure element having substantially no or very low solid-solubility with respect to the copper at a room temperature is impregnated.

Vacuum switch and method of manufacturing the same

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.

A vacuum interrupter of parallel magnetic field electrode type comprising a pair of separatable arc electrodes disposed within a vacuum vessel, with each being provided on its back side with a conductive rod extending outwardly of the vacuum vessel. Coil electrodes are electrically connected between the associated arc electrode and rod for applying parallel magnetic fields to arc, and slits are formed in the arc electrodes for suppressing eddy currents of the arc electrodes resulting from the parallel fields. A reinforcement member of an electric conductivity higher than a main surface portion of the arc electrode is provided on the back side of the arc electrode opposite to said main surface portion so that the resulting arc current flows uniformly through the reinforcement member so that a higher interruption efficiency can be obtained for the vacuum interrupter.

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Hitachi, Japan

Kiyoji Iwashita