UPS is a backup power supply. During normal operation, it only serves as a channel, that is, the computer uses mains power.

At the moment of power outage, the UPS will switch to battery discharge mode. At this switching moment, the computer's power supply has a certain delay capability. The delay time is determined by the characteristics of the power supply itself. The value may be tens of milliseconds to hundreds of milliseconds, and the UPS itself also needs a certain amount of time to switch. Similarly, the switching time is different for different products.

If the UPS switching time is relatively long, and the computer power supply itself is of poor quality, the delayed load capacity will be relatively short, which will result in the UPS not switching to the backup power state after the mains power outage. At that time, the computer can no longer supply power normally, which will cause a power outage to the computer.

At the same time, other reasons may also cause the UPS to fail to function properly:

The computer power is too large

The UPS or the computer power supply is poor