| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To avoid an entire system shutdown by removing a trouble due to abnormal switching operation between a direct power supply circuit and a power converter. <P>SOLUTION: A plurality of sets of uninterruptible power supplies each comprising a power converter, a direct power supply circuit, and a switch for switching them without interruption are connected with a bus through individual maintenance switches. When a command for switching AC power supply to the bus from one or more direct power supply circuits to a power converter is issued, a command for turning the output side switch of the power converter on is issued based on that command and when the output side switch of the power converter is turned on, a command for turning the output side switch of the direct power supply circuit off is issued. If the output side switch of the direct power supply circuit is not turned off, the power converter is stopped. An off command is issued to a maintenance switch corresponding to the direct power supply circuit on condition that the power converter is stopped, the switch is abnormal, any one power converter is normal, and AC power is supplied to the bus. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
