Ngk Insulators, Inc.

Naoki Tanaka

Hiroyuki Katsukawa

Toshiyuki Kawaguchi

Katsuro Shinoda

Hiroyuki Abe

Kazumi Nakanishi

Yasuhisa Sakurai

Genzo Kimura

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

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

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

Growing community of inventors

Kuwana, Japan

Naoki Tanaka