ELTECH Offline UPS system is the basic solution for non-critical applications. It filters the power from the mains outlet to your devices. These units will transfer to the battery backup when the voltage from the mains drops below the normal level (commonly called a sag or brownout) or increases beyond the normal level (surge). The inverter is “off” until needed to convert the battery power into useful electricity. It is also a basic solution that protects non-critical hardware and data against three out of the nine power problems. These UPSs operate in Offline mode.