The UPS Micropower 800VA emergency power supply signed with the Green Cell logo is a line-interactive power supply type, characterized by 480W and 800VA apparent power. The input and output voltage is 230VAC. The use of this form of power generation enables the power supply of devices sensitive to input current characteristics. UPS Micropower 800VA Green Cell is equipped with the AVR Bust&Buck function, which is designed to automatically regulate voltage. With this option, UPS can keep the nominal output voltage at any time without switching to battery work in case of a continuous excess or power supply voltage reduction. In addition to this very useful solution with which engineers equipped the UPS power supply, there was also a cold start function. It forces battery mode operation without previously connecting UPS to the power grid. It works in situations where we are forced to run the computer to copy important data from it. Among the functions used in the UPS 800VA emergency power supply are also: Auto Reset and charging in automatic off mode. The UPS 800VA emergency power supply was made in line-interactive technology, which means that the device switches to battery mode very quickly when the voltage loss is detected. This was possible by using a parallel connection of the inverter to the power supply while charging battery cells. UPS line interactive emergency power supplies are characterized by very high efficiency and are successfully used to secure components such as servers, workstations, routers, access points, etc.