| 摘要 |
PURPOSE:To provide a power disturbance detection relay which does not operate at the time of a failure in a power system but operates at the time of a system disturbance. CONSTITUTION:A power flow variation detecting unit 12 and a power continuation deciding unit 13 are provided. The power flow detecting unit 12 compares the present power flow value of a power system with the power flow value a first designated time, longer than the current continuation time at the time of a failure in a power system, before. If the difference exceeds a designated value, the power flow detecting unit 12 generates a detection output. If the output of the power flow detecting unit 12 continues for a time longer than a second designated time which is longer than the failure current continuation time at the time of the failure in the power system and shorter than a half of a power disturbance period, the power continuation deciding unit 13 generates a relay output. |
