The main function of UPS power supply is to keep the building intercom system from power failure. Under normal conditions, it is in the state of charging. When the power is cut off, the UPS power supply is in the state of supplying power to the system. At present, the manufacturer of the building intercom system is generally different from the UPS battery. The main reason is that the power consumption of the visual system is too large, and the general small-capacity UPS battery can not guarantee the use time!