Hitachi, Ltd.

Minoru Kanoi

Hiroshi Inoue

Yasuro Hori

Kazuo Nishijima

Yuzuru Imamura

Mitsuru Nakamura

Junzo Kawakami

Hiroyuki Kudo

Kiyoji Iwashita

Terunobu Miyazaki

Toru Takei

Saburou Yasukawa

Masahiro Watanabe

Masahiko Amano

Tooru Tanimizu

Shuichi Kikukawa

Toshifumi Yoshikawa

Yuzuru Kamata

Saburo Yasukawa

Syuya Hagiwara

Takuya Miyo

Kazuyuki Seino

Makoto Tazawa

Shinji Tanifuji

Masaaki Maejima

In order to provide a vacuum switch suitable for a distribution and transformation system compatible between structural simplicity and reliability and a vacuum switchgear using the vacuum switch, the vacuum switch comprises switching portions installed in a grounded vacuum container; and a breaker, a grounding switch and an isolator as things having the switching portions, wherein the vacuum container is divided into at least two chambers, and the switching portion of the breaker is disposed in one of the chambers and the switching portions of the grounding switch and the isolator are disposed in the other of the chambers through an insulation body.

Vacuum switch and vacuum switch gear using the vacuum switch

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.

In a control system for a power transmission and distribution system, a plurality of distributed power supplying and receiving units each including a control unit are provided and connected along a power distribution line. The power supplying and receiving unit function to generate active and reactive powers of fundamental and higher harmonic waves to supply and receive the same to and from the power distribution line. A first central control unit controls the power distribution line and is designed to store information relating to the configuration of the power distribution line, to collect information with regard to instant open and close conditions of respective disconnecting switches connected for sectioning the power distribution line, and with regard to current electrical quantities on the power distribution line. Individual control command signals specific to the respective power supplying and receiving units are produced based on the stored and collected information and the respective power supplying and receiving units are controlled so that a desired target condition of the power distribution line is achieved autonomously within the power distribution line through an optimum cooperation control of the units.

Control system for power transmission and distribution system

A power stoppage minimizing system for a distribution line and a method of using a distribution line minimize a power stoppage section and a power stoppage time when a short circuit occurs in the distribution line, and employs a first and a second distribution line each connected through a circuit breaker to a corresponding bus and each having switches in position thereon; a normally open tie point switchgear provided between adjacent ends of the first and second distribution lines; a protective relay for opening, when a short circuit has occurred, the circuit breaker a fixed time after the occurrence of the short circuit on the first distribution line; a first unit for opening a switch on the side of a power source and nearest a point where the short circuit has occurred; a second unit for opening, after the switch is opened by the first unit, a switch on the side of a load nearest the switch opened by the first unit; and a third unit for closing the tie point switchgear after the opening of the switch by the second unit, the opening of the switch by the first unit being made within a fixed interval of time for the protective relay. Thus, the short circuit section is located and the switches before and after the short circuit section are opened. The tie point switchgear is then closed to thereby minimize the power stoppage section and time when the short circuit has occurred.

Power stoppage minimizing systems for distribution lines and methods of

Upon the occurrence of a fault on the first distribution line, a faulty section on the distribution line is pinpointed, then a tie point switchgear at the tie point between the first distribution line in which the fault occurred and the other normal second distribution line is closed to form a loop distribution system. Then, a switchgear adjacent to the fault point on the first distribution line is opened. An opposing switchgear adjacent to the fault point is opened on the condition that the fault occurrence continues after having been linked to the second distribution line. The above procedures are executed before the opening of the circuit breaker installed on the distribution bus bar.

Service interruption minimizing system for power distribution line

A noise-reduction device for a stationary induction apparatus which device comprises a sound insulation panel attached to reinforcing channels provided at the periphery of a tank of the stationary induction apparatus so as to block noises emitted from the outer surface of the tank, a weighty body attached to the sound insulation panel for reducing vibrations of the sound insulation panel and a dynamic damper of which the natural frequency can be adjusted to be made equal to the vibration frequency of the weighty body so as to cancel the vibrations of the weighty body.

Noise-reduction device for stationary induction apparatus

A static induction apparatus including a vessel for containing a main body of the static induction apparatus, a plurality of reinforcing support members secured to side plates of the vessel and a sound reducing structure. The sound reducing structure includes a plurality of sound reducing members supported between the reinforcing support members and each including a sound insulating panel composed of high damping metal plate, a resilient plate formed of thin metal sheet material interposed between the sound insulating panel and the reinforcing members, and a weight member secured to the vicinity of the boundary between the sound insulating panel and the resilient plate.

Static induction apparatus

A vibration/noise reducing device for applying contrary vibrations/sound waves whose phases are substantially opposite to vibrations/noises generated from an electrical apparatus is disclosed, in which the vibrations/noises from the electrical apparatus are sensed by a sensor, the sensed analog time-domain signal is A/D converted, the resulting digital time-domain signal is then Fourier-transformed, the resulting Fourier-transformed digital frequency-domain signal is modified in its amplitude/phase to produce a second digital frequency-domain signal for generating a vibration/noise reducing control signal, the second digital-frequency-domain signal is inverse-Fourier-transformed, the resulting inverse-Fourier transformed second digital time-domain signal is D/A converted, and the resulting analog time-domain signal is used as the control signal to generate the contrary vibration/sound waves to be applied to the vibrations/noises.

Vibration/noise reduction device for electrical apparatus

This invention relates to an isolator for a large-sized static induction apparatus such as transformer and reactor. The static induction apparatus wherein a sound insulation panel is mounted through an elastic body on a reinforcing channel which is disposed on a side plate of an oil tank receiving a main device of the apparatus therein, is characterized by disposing a looped weight beam near that part of the sound insulation panel on which the elastic body is installed. With such construction, noise can be effectively reduced while imparting a satisfactory supporting strength to the mounting part of the sound insulation panel.

Growing community of inventors

Tokai-mura, Japan

Minoru Kanoi