A Line- Interactive UPS offers backup function and automatic voltage regulation (AVR). AVR regulates voltage to the appropriate level by decreasing it during surges or swells or increasing it during a sag or burnout. The advantage is a better protection for sensitive IT- and household equipment and avoids damage caused by voltage up- and downturn. AVR function also benefits the battery lifetime. As long as voltage level is not lower than 70% to 90%, or higher than 110% to 125% AVR will adjust voltage to normal level. I case the voltage drops to a lower or higher level, the UPS will directly switch to battery mode to avoid dropouts and damage of the connected equipment. Line- Interactive UPS offers USB port (RS-232) to connect to a multitude of operating systems for monitoring voltage, power and battery status. Line- Interactive UPS are designed for medium cost application with moderate load levels