UNINTERRUPTIBLE POWER SUPPLY

PROBLEM TO BE SOLVED: To provide an uninterruptible power supply which employs a storage battery discharge operation method that sets a discharge termination voltage based on a load capacity to prevent overdischarge by a storage battery, which is not influenced by noise, storage battery voltage, and current pulsation, and ensures a more proper power failure operation for a longer period. SOLUTION: The uninterruptible power supply includes an AC-DC power converter which converts AC power from a commercial power supply into DC power, an inverter which converts rectified DC voltage into AC voltage to supply DC voltage to a load, and a storage battery used as a backup power source. The equivalent amount of load of the storage battery is measured, and the discharge termination voltage of the storage battery is set in accordance with the size of the equivalent amount of load. When the voltage of the storage battery drops to the discharge termination voltage, the power failure operation is stopped when an operation time determined by the equivalent amount of load elapses. COPYRIGHT: (C)2011,JPO&INPIT