| 摘要 |
<p>PURPOSE:To eliminate overprotective function by providing CT element at the exterior of enclosed bus bar container containing circuit breaker, and grounding it at the bushing side when detecting the fault through a differential relay. CONSTITUTION:When protecting the circuit connecting the power source side 2 and the load side 3 through the circuit breaker 1 by means of CTs 4-7 and differential relays 8, 9, CT elements 5A, 6A are provided on the outer circumference of enclosed bus bar containers 16, 17 containing circuit breaker 11, while lower metals of the bushings 18, 19 are grounded through grounding wires 24, 25. Consequently the current flowing through bus bar container 16 due to shortcircuit fault at point C flows reversely with the current flowing through the bushing conductor 20 and CT element 5A detects the difference, the direction and the magnitude become same with those of CT 7 at load side 3 resulting in proper protection without causing over protective function.</p> |
