| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an uninterruptible power supply system which includes two sets of uninterruptible power supply devices each composed of a power conversion circuit and a bypass power supply for feeding power to a load by selecting one set out of the two uninterruptible power supply devices, and can more surely feed power to the load. <P>SOLUTION: When the power feed switching device 9 issues a new command for feeding power to the load 6 from the uninterruptible power supply device 8 when a contactor 52 is in a closed state, that is, when the power is fed to the load 6 from the uninterruptible power supply device 7, the contactor 52 is brought into an open state, and a thyristor switch 53 is switched to an on-state on condition that a switching decision circuit 91 to which an output voltage of the uninterruptible power supply device 7 and an output of a synchronization decision circuit 71, and an output voltage of the uninterruptible power supply device 8 and an output of a synchronization decision circuit 81 are input has output a synchronous signal. After that, by closing a contactor 54 after waiting for the contactor 52 to be brought into a complete open state, the switching operation can more surely be finished without causing instantaneous interruption and a shock. <P>COPYRIGHT: (C)2010,JPO&INPIT |
