Title:
GROUND FAULT DETECTOR FOR MOTOR PROTECTION RELAY
Document Type and Number:
Japanese Patent JP3419589
Kind Code:
B2
Abstract:
PURPOSE: To prevent unnecessary function of a motor protection relay by suppressing saturation of a current transformer due to the DC component of surge current at the time of starting a motor.
CONSTITUTION: A current transformer 3 connected with a motor feeder 8 is connected, on the secondary thereof, with a motor protection relay 5 having an element 9 for detecting ground fault of the motor feeder 8. A peak measuring unit 7a measures the number of peaks in each phase current flowing through the current transformer 3 and short-circuits the opposite terminals thereof for a predetermined cycles when the number of peaks in each phase current is equal within a predetermined time.
More Like This:
Inventors:
Koichi Seto
Application Number:
JP12391995A
Publication Date:
June 23, 2003
Filing Date:
May 23, 1995
Export Citation:
Assignee:
Mitsubishi Electric Corporation
International Classes:
H02H7/08; H02H3/34; H02P1/26; (IPC1-7): H02H7/08; H02H3/34
Domestic Patent References:
| JP8126188A | ||||
| JP2114820A | ||||
| JP63302722A | ||||
| JP63302723A |
Attorney, Agent or Firm:
Hiroaki Tazawa (2 outside)
Previous Patent: AUTOMATIC IMAGE READER
Next Patent: SILICON ETCHING METHOD, AND MANUFACTURE OF CCD SOLID IMAGE PICKUP DEVICE USING THIS METHOD
Next Patent: SILICON ETCHING METHOD, AND MANUFACTURE OF CCD SOLID IMAGE PICKUP DEVICE USING THIS METHOD