| 摘要 |
PROBLEM TO BE SOLVED: To provide an overcurrent relay device which can eliminate an accident in the same time regardless of an accident aspect (three-phase short circuit accident and two-phase short circuit accident). SOLUTION: The overcurrent relay device is used for the protection of a power transmission line in a power system at a short circuit accident, and comprises: operation time limit determination means 12<SB>1</SB>to 12<SB>3</SB>, 13<SB>1</SB>to 13<SB>3</SB>and 14<SB>1</SB>to 14<SB>3</SB>which obtain operation time limits of the overcurrent relay device according to an operation time limit characteristic curve which decides the operation time limit of the overcurrent relay device; and an accident aspect determination means 15 which determines whether the accident is the three-phase short circuit accident or the two-phase short circuit accident on the basis of an amplitude value of an accident current at the short circuit accident. When the determination result by the accident aspect determination means 15 shows that the accident is the two-phase short circuit accident, the operation time limit determination means 12<SB>1</SB>to 12<SB>3</SB>, 13<SB>1</SB>to 13<SB>3</SB>and 14<SB>1</SB>to 14<SB>3</SB>obtain the operation time limits of the overcurrent relay device according to the operation time limit characteristic curve on the basis of a value obtained by dividing the amplitude value of the accident current at the short circuit accident by 3<SP>1/2</SP>/2. COPYRIGHT: (C)2008,JPO&INPIT
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