The main advantage of the uninterruptible power supply is its uninterrupted power supply capability. When the mains AC input is normal, the UPS rectifies the AC power into DC power, and then inverts the DC power into a stable and impurity-free AC power for use in the rear stage load. Once the mains AC input is abnormal, such as undervoltage or power failure or the frequency is abnormal, the UPS will activate the backup energy-battery, and the UPS rectifier circuit will be turned off. Correspondingly, the battery's DC current will be inverted to be stable. The alternating current of impurities continues to be used for the rear stage load. This is the origin of the UPS uninterrupted power supply.
Of course, the uninterruptible power supply time of the UPS is not unlimited. This time is limited by the amount of energy stored in the battery itself.