| 摘要 |
PURPOSE:To effectively protect a power distribution system by operating a semiconductor device mounted at a power distribution line at a high speed at the time of an accident, short-circuiting or ground-faulting the system, outputting a current flowing to the device or a voltage by a detector, and monitoring it with respect to ON, OFF of a trigger. CONSTITUTION:When an optical CT 10 detects a defective current, a controller generates a trigger signal to turn ON a semiconductor device 5, and to shorten among phases, thereby protecting a power distribution route. The output of the detector 11 is sent to a discriminator to decide whether the device 5 is normally operated or not. After ON of a protection switch 8 is confirmed, in the case where the trigger is ON, if the current flowing to the detector 11 is an allowable value, it is understood that the device 5 is normally operated. If the current is much smaller than the allowable value even if the trigger is ON, it is judged as firing mistake of the device 5. In this case, the trigger is turned OFF, a breaker 12 is opened, the switch 8 is then opened to disconnect the device 5 from its power distribution system, and a normal trouble repairing is conducted. |
