| 摘要 |
PURPOSE:To diagnose abnormality by detecting discharge of a storage battery caused by a failure such as of a rectifier during normal ac input and to prevent unnecessary discharge of the storage battery by switching to power supply from an ac reserve power source. CONSTITUTION:A DC-CT21 detects discharge current of a storage battery 2 by supplying dc power from the storage battery 2 to an inverter 4. Discharge current of the storage battery 2 detected by the DC-CT21 is inputted to an abnormality detector 22, which diagnoses abnormality by a predetermined or more time of duration of the discharge of the storage battery 2 in spite of normal ac input power source and gives abnormality detected signal to a switch control circuit 23. The switch control circuit 23 receives this abnormality detected signal and controls selector switches 7, 8 for nonhit switching from power supply by the inverter 4 to power supply by a reserve ac power source 6, thereby bringing the storage battery 2 and the inverter 4 into a nonload state. This process can continue supply to a load 9 and prevent discontinuity of unnecessary discharge of the storage battery 2. |
