Why is it necessary to use a 3 phase transformer when going from 3 phase to single phase?
Single phase is obtained from a 3 phase system by simply connecting to any two wires in the 3 phase system. This applies to a 3 phase system whether it is 3 phase/3 wire or 3 phase/4 wire. Once single phase is obtained as explained above, then only a single phase transformer is required. Transformers cannot be used to even out a single phase load so that it will be distributed equally on all 3 phases of a 3 phase system. Transformers may be used to change any number of phases to any other number of phases other than one.
