When should we use a single or 3 phase UPS?
The choice of either a single phase or three phase UPS depends on the load that needs to be protected. UPS with single phase inputs are typically used when the protected load is less than 10kVA. When the total load to be protected is more than 10kVA, typically a UPS with three phase input is chosen, even where the inverter output is single phase. Larger UPS units with three phase input and three phase output are used when the load is more than 20kVA and the loads can be either single phase or three phase in nature. Three phase UPS are more compatible with a three phase DG set and these UPS systems can also be used to feed single phase loads, and with good load balancing, the DG does not need to be oversized.