Electric products are susceptible to damage from sudden power failures. Power failures may be brief, only one-tenth of a second, but they may be destructive to electronic products. To prevent this from happening, uninterruptible power supplies are widely used in Computer systems, communication systems, and other electronic equipment. Uninterruptible power supplies convert AC power to DC power, and then charge the battery. In this way, the battery can make up for the intermittent power outage during a power outage. This text mainly talks about:. ['Damage to electricity caused by power failure.', 'How to use a battery to prevent power failure.', 'Measures to prevent power outages from damaging electronic products.', 'Working principle and function of uninterruptible power supply.']