Can I connect a single-phase transformer to a three-phase source?
Yes, and the transformer output will be single-phase. Simply connect any two wires from a 3- or 4-wire source to the transformer’s two primary leads. Three single-phase transformers can be used for three-phase applications. They can be used in delta-connected primary and wye or delta-connected secondary. To avoid an unstable secondary voltage, NEVER connect wye primary to delta secondary.
