Ngk Insulators, Inc.

Other

Toshiyuki Kawaguchi

Hiroyuki Katsukawa

Katsuro Shinoda

Kazumi Nakanishi

Naoki Tanaka

Hiroyuki Abe

Takashi Isozaki

Yasuhisa Sakurai

Isao Nakajima

Noriyasu Oguri

Hiroshi Harada

Ryuta Yamamoto

Seigo Yokoi

Shigeo Yokoi

Yuichi Kakizaki

Genzo Kimura

Tomio Hayashi

A system for detecting a fault occurred within a substation and judging a location of the fault including optical current sensors each having a Faraday element arranged on a top of an insulator post of a bus disconnecting switch, a magnetic core arranged to surround a terminal plate of the disconnecting switch to generate a magnetic field corresponding to a current passing through the terminal plate, a laser diode for emitting a laser light beam, an optical fiber for guiding the laser beam to the Faraday element, a photodiode, and an optical fiber for guiding the laser beam transmitted through the Faraday element to the photodiode. The photodiode supplies a signal representing the current passing through the terminal plate to a fault location judging circuit in which the fault location within the substation is judged from the signals from the photodiodes.

System utilizing optical current sensors for detecting fault location in

In a system for transmitting an electrical power supply by means of an over-head power transmission line supported by power transmission towers, a fault such as a short-circuit fault and a ground fault is detected by providing optical current sensors having opto-magnetic elements and opto-electric field elements on respective conductors of the transmission line to detect a fault current and fault voltage on the basis of the Faraday's effect and Pockel's effect. Light beams passing through the elements are modulated by the magnetic fields induced by the currents passing through the conductors and the voltages on the conductors, and thus include information about the current and voltage. There is further provided a circuit for calculating a distance to a fault point in accordance with the detected current, voltage and a phase difference therebetween and a known impedance of the power transmission line. The thus calculated distance to the fault point is displayed on display means which is arranged at the power transmission tower or the substation.

Apparatus for detecting faults on power transmission lines

An optical current transformer particularly useful for a fault location system for a power supply system and substation, including a casing which can be detachably secured to a plurality of wire conductors which conduct currents of the same phase. Within the casing a plurality of Rogowsky coils are arranged such that when the casing is secured to the wire conductors, each Rogowsky coil is wound around respective wire conductors. The Rogowsky coils are connected in series with an air-core coil and an optical current sensor having a Faraday element is arranged within a space of the coil such that the Faraday element is subjected to a magnetic flux generated by the coil. A magnitude of the magnetic flux is optically detected by the Faraday element to measure a total sum of currents conducting along the wire conductors.

Optical current transformer

A helmet with two-way radio communication faculty including a cap-like outer shell made of hard and electrically insulating plastic material, a cap-like shock absorbing member arranged within the outer shell, an ear-pad member secured to one side edge of the outer shell, a transmitter unit arranged in a top recess formed in an outer surface of the shock absorbing member at its top portion, a receiver unit arranged on an inner surface of the ear-pad member, a battery unit arranged in a side recess formed in the outer surface of the shock absorbing member at its side which is opposite to a side on which the ear-pad member is secured to the outer shell, a transmitting dipole antenna made of a metal foil secured on an inner surface of the outer shell at its one side with the aid of an electrically insulating adhesive tape, and a receiving dipole antenna made of a metal foil secured on the inner surface of the outer shell at its other side with the aid of an electrically insulating adhesive tape.

Helmet with two-way radio communication faculty

Optical fiber-containing insulators each comprises an insulator body having a through hole provided in its central portion and extending along an axial direction thereof, an optical fiber core wire passing through the through hole, an insulating material filled between an inner peripheral surface of the through hole and the optical fiber core wire, and arrangements for preventing the filled insulating material from axially protruding out of the insulator body even at high temperature or spacers for holding the optical fiber core wire at the central portion of the through hole of the insulator body.

Optical fiber-containing insulators

A system for supervising and guiding workers at various places in a construction such as an underground substation, underground market, building, or tunnel is disclosed which includes a number of receivers arranged in a number of sections of the construction for receiving infrared radiation emitted from workers to produce a detection signal, a detection device arranged in a central control room for processing the detection signals supplied from the receivers to detect positions of workers in the construction, and communication devices provided in each section and the central control room for providing the workers with various kinds of instructions, commands and messages for preventing a disaster and escaping an emergency.

System for supervising and guiding persons in construction

A work helmet for effecting an intercommunication between workers as well as between a central control room and respective workers, especially used for informing each workers of guide information adequate for emergency escape when a disaster occurs is disclosed. To this end, the work helmet includes a light-receiving element for receiving a light signal modulated with the guide information, an earphone for reproducing audibly the guide information, a light emitting element for emitting an outgoing light signal modulated with a speech signal supplied from a microphone, and an oscillator for generating a carrier having a frequency specific to the helmet, on which carrier said speech signal is modulated, so that the outgoing light signal is always modulated by the carrier serving as a helmet identifying signal by means of which the central control room can recognize and identify the worker wearing the helmet.

Work helmet having transmitter-receiver for light signal

A rod-type insulator is provided with the optimum withstand voltage characteristics under a contaminated condition by selecting the ratio of the leakage distance per shed to the shed pitch to be between 3.8 and 5.0 and also selecting 4.5.ltoreq.l/p.ltoreq.6.0, where p is the distance between the adjoining sheds, i.e., the distance between a given point on the lower surface of one shed and another given point on the upper surface of the other opposing shed, and l is the leakage distance between the two points.

Growing community of inventors

Inuyama, Japan

Toshiyuki Kawaguchi