UPS is an uninterruptible power supply with energy storage device. It is mainly used to provide uninterrupted power supply to some devices that require high power stability. When the mains input is normal, the UPS will stabilize the mains and supply it to the load. At this time, the UPS is an AC voltage stabilizer, and it also charges the battery inside the machine; when the mains is interrupted (accidental power failure) When the UPS is switched on, the UPS will immediately supply 220V AC power to the load by switching the DC power of the battery to the load, so that the load can maintain normal operation and protect the software and hardware of the load from damage. UPS devices usually provide protection against overvoltage or undervoltage.