| 摘要 |
PURPOSE:To shorten the operating time by judging effective power when a plurality of overcurrent relays arranged in a power system detect overcurrent and judging whether the current obtained through a predetermined operation is an overcurrent in case of an overload. CONSTITUTION:When a plurality of overcurrent relays connected with a power system detect overcurrent, effective power passing through that relay is judged in STEP 6. If judgement is made for effective overload power, the current at that time is obtained in STEP 7 based on a formula 1=(P<2>+Q<2>)<1/2>/V, where P is effective power, Q is reactive power and V is voltage. It is judged whether the current 1 exceeds a predetermined value in STEP 8, and an abnormal signal is produced in STEP 9 if the current I exceeds the predetermined value. By such arrangement, processing amount necessary for simulation is reduced resulting in reduction of computor load. |
