| 摘要 |
PURPOSE:To provide a highly reliable power supply apparatus by which frequent repetition of making/breaking of the voltage of a backup battery can be avioded and harmful influence upon electric equipment can be avioded. CONSTITUTION:If the voltage Ve of a battery 6 is higher than a reference voltage Vref when a commercial AC power supply 1 is interrupted, the voltage Ve of the battery 6 is cost into output terminals 3a and 3b. If the service interruption is continued and the voltage Ve of the battery 6 becomes lower than the reference voltage Vref, the voltage Ve is disconnected from the terminals 3a and 3b. At that time, the level of the reference voltage Vref is changed to rise and the voltage Ve of the battery 6 does not exceed the reference voltage Vref as far as it is not recovered to a sufficiently high level. The disconnected state of the voltage Ve of the battery 6, therefore, is continued. |
