Offline UPS, here and there depicted as standby power supply (SPS) are frameworks where the heap is taken care of straightforwardly from the crude mains during ordinary tasks rather than the inverter yields. At the point when the mains supply falls flat or varies outside of the UPS’s working window, a hand-off interfaces the heap to the inverter yield (bringing about a 4-8ms move time). In typical activity, with mains supply present, both yield voltage and recurrence will follow the information voltage and recurrence separately.