| 摘要 |
PROBLEM TO BE SOLVED: To check, in operation state of the device, the existence of breakage of the main circuit element of an instantaneous voltage drop countermeasure device which detects the voltage drop on the circuit side and cuts off the circuit side instantaneously, being installed between a private generator linked to the circuit and the circuit. SOLUTION: The off command of the thyristor switch of the device is outputted by the operation of a manual push button or periodically with a control circuit (S1), and the three-phase current of the main circuit is detected (S2), and the comparison between a detection current ID and the current set value Iset is performed (S3). Next, if all the three phases of the main circuit are roughly zero in currents, it is judged that the system is normal, otherwise it is judged to be abnormal, regarding it as the short circuit of the main circuit element, and a thyristor switch on command is outputted, whereby the breakage check is completed. This check is performed by turning off the thyristor switch for one to several cycles, so hindrance does not occur during circuit parallel off period or at the time of power on after parallel off. |
