In many cases three phase power is available on site, when single phase loads are large or not easily balanced with loads on other legs of the three phase circuit. It may be advantageous to let the UPS balance the three phase currents and supply a single phase load on the output. Since this may avoid an additional transformer, as well as save space and rewiring costs, it can have great appeal. The single phase output voltage can also be at a different voltage than the input. When this is the case, a considerable amount of external equipment is eliminated including;
You should note that if the unit is in bypass, the load will be unbalanced. As a special case, when single phase 120V loads are required, the load can be shared between two phases when on bypass.