| 摘要 |
PURPOSE:To minimize the lowering of service due to power interruption by shutting down an inverter to break the power supply from the stringing and firing a switching element when a capacitor terminal voltage has become lower than the No.1 specified value. CONSTITUTION:Low-voltage detectors 10-12 and overvoltage detectors 13-15 monitor the terminal voltage of filter capacitors 7-9. A voltage fluctuation detector 5 issues a voltage fluctuation signal when a stringing voltage has become higher than the upper limit or lower than the lower limit. When only the voltage fluctuation detector is actuated due to a transient stringing voltage fluctuation while neither the low-voltage detectors 10-12 nor overvoltage detectors 13-15 are actuated, a system will shut down inverters 16-18 only by judging the trouble as 'slight', and restart the inverters 16-18 immediately when the line voltage recovers. The system judges a trouble 'serious' when either any of the low-voltage detectors 10-12 or overvoltage detectors 13-15, is actuated singly. |
