| 摘要 |
PROBLEM TO BE SOLVED: To rationally supply power to a load that requires a backup operation for a specified period of time after the occurrence of a service interruption and a load that ordinarily operates on commercial power supply and requires a backup operation for a short period of time after the occurrence of a service interruption. SOLUTION: When an alternating-current power supply 1 is under normal conditions, an alternating-current reference voltage in phase with the commercial voltage of the alternating-current power supply 1 is output from a reference voltage circuit 21 according to a synchronizing signal output from a synchronization circuit 26. An alternating-current voltage in phase with the commercial voltage is output from an inverter 3. A load 4 is supplied with the alternating- current reference voltage and the alternating-current voltage, and a load 7 is supplied with the commercial voltage of the alternating-current power supply 1 through a change-over switch 6. If the alternatingcurrent power supply 1 is judged to be interrupted at a service interruption detection circuit 25 and a command S2 is output, the load 7 is supplied with the output voltage of the inverter 3 through the change-over switch 6 only for a short time. |
