Title:
METHOD AND DEVICE FOR GROUND-FAULT LINE SELECTION AND PROTECTION RELAYING
Document Type and Number:
Japanese Patent JP3425305
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To detect the fault current of a ground-fault which occurs in a system by offsetting a zero-phase circulating current by means of a lesser number of line selecting and discriminating elements even when another system of a different frequency is installed in parallel.
SOLUTION: An input circuit 11 fetches the zero-phase voltage V0 of a system and the difference current J0 between the zero-phase currents of the first and second lines of the system after digitization and a memory 12 delays the difference current J0 by a period of time TD longer than the discriminating time required for discriminating a ground-fault. Then an operator 13 finds the difference between the inputted difference current J0 and the output of the memory 12 and calculates the fault current of a one-line ground fault from which a zero-phase circulating current is eliminated.
Inventors:
Fumio Iwatani
Isao Wachi
Yasutaka Suzuki
Ichinose Norifumi
Takafumi Maeda
Isao Wachi
Yasutaka Suzuki
Ichinose Norifumi
Takafumi Maeda
Application Number:
JP23211496A
Publication Date:
July 14, 2003
Filing Date:
September 02, 1996
Export Citation:
Assignee:
株式会社日立製作所
東京電力株式会社
東京電力株式会社
International Classes:
G01R31/02; H02H3/16; H02H3/36; H02H7/22; (IPC1-7): H02H3/36; H02H3/16
Domestic Patent References:
| JP6225441A | ||||
| JP5854821A | ||||
| JP63304174A | ||||
| JP5866528A |
Attorney, Agent or Firm:
Yoshihiro Takasaki
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