Mitsubishi Denki Kabushiki Kaisha

Mitsubishi Electric Corporation

Toshio Anzai

Satoru Ishizaka

Hiroyuki Kimata

Yoko Toda

Keita Fujimaru

An electronic device comprises a plurality of printed circuit boards having signal GNDs, a metal bar which electrically connects to the respective signal GNDs of the plurality of printed circuit boards, and a card basket which houses the plurality of printed circuit boards and the metal bar and serves as a frame GND. The electronic device also comprises a dielectric between the card basket and the metal bar. The metal bar, the card basket, and the dielectric constitute a noise control capacitor having specific frequency characteristics. By the specific frequency characteristics, the noise control capacitor releases electromagnetic noise occurring in the respective signal GNDs to an outside and shields external noise generated outside.

Electronic device and electromagnetic noise control method

Function of an equipment control apparatus is changed from outside of the equipment control apparatus by means of a communication method of higher security than that of a monitoring system operating via a Web communication net: the equipment control apparatus being provided on the side of facility equipments constituting a power system and controlling the facility equipments; and the monitoring control apparatus being provided outside of the equipment control apparatus and obtaining internal information about the equipment control apparatus via the Web communication net to monitor a state of the power system from the internal information.

Power system management method and power system management system

A protective relay for use in deciding an operating condition of an electric power system with a digital computer and protecting equipment connected to the electric power system. Basically, the protective relay is required to operate under an internal fault and not to operate under an external fault. The protective relay has a first comparison and decision element for determining whether the fault is an internal fault or an external fault by comparing a ratio between a vector summation (actuating quantity) and its maximum value (restraining quantity) in respect to an instantaneous electric current in the system. A second comparison and decison element decides whether the system is in a fault condition or not by detecting the actuating quantity in reference to its level with an output of the second comparison and decision element being inhibited by the output of the first comparison and decision element. The external fault is instantaneously judged by the first comparison and decision element and if a current transformer becomes saturated under the external fault and an excessive actuating quantity is generated, the relay is constructed with a return timer or a memory of the restraining amount in such a way as to continue inhibiting the second comparison and decision element to inhibit an erroneous operation of the protective relay.

Growing community of inventors

Tokyo, Japan

Toshio Anzai