| 摘要 |
PROBLEM TO BE SOLVED: To enable the continuation of power supply to large consumers even in the case of accidents at loop-constituting distribution lines, general consumers or distribution lines outside a loop system when the distribution lines are constituted of the loop system. SOLUTION: A protection system of the loop system includes feeder protective devices 15 which judge a short-circuit failure, a ground fault, and an overload state in the distribution lines drawn out of a substation 11 and control the opening and closing of circuit breakers of the substation, and a loop point protective device 16 which judges a failure/good condition of the loop system obtaining an electrical quantity from an instrument transformer 17 provided at a loop point of the loop system and controls the opening and closing of a loop point circuit breaker of the loop system. The loop point protective device 16 opens the loop point circuit breaker CB2 immediately against a short-circuit in the distribution lines inside the loop system and after a predetermined time against a ground fault, and closes the loop circuit breaker CB2 after a predetermined time again when the good condition of the distribution lines inside the loop system is detected after the loop circuit breaker CB2 is opened. COPYRIGHT: (C)2011,JPO&INPIT
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