| 摘要 |
PURPOSE:To preferentially short-circuit effectively even in case of accidents of two or more phases in which the operation of an own terminal insufficient voltage relay cannot be expected by receiving the operating condition of an opponent terminal insufficient voltage relay, and generally judging the responses of the own terminal insufficient voltage relay and the opponent terminal insufficient voltage relay. CONSTITUTION:An own terminal preferential short-circuit is employed under the condition that accidents of one or more phases are detected from the elements of own terminal short-circuit insufficient voltage relay 6 and opponent terminal short-circuit insufficient voltage relay 21. Accordingly, if the relay 21 is operated, OR logics 11b, 11a attains '1' level, and the output of NOT logic 12 attains '0' level. Thus, the output of AND logic 13 is locked. Even in case of an incorrect response of a ground-fault current differential relay 5a, unnecessary tripping can be effectively stopped. Thus, a preferential short- circuit can be employed even in case of an accident in which the relay 6 cannot be operated by the operation of the relay 21. |
