Three Phase Transformer Connections and Basics A transformer can not act as a phase changing device and change single-phase into three-phase or three-phase into single phase. To make the transformer connections compatible with three-phase supplies we need to connect them together in a particular way to form a 240V Transformer Wiring Diagram - Wiring Forums Looking for details concerning 240V Transformer Wiring Diagram? you are right here. You may be a technician that wants to look for recommendations or resolve existing problems. Or you are a trainee, or maybe even you that simply would like to know about 240V Transformer Wiring Diagram. Transformer Wiring Diagrams Three Phase King County Property 3 Phase Transformer Wiring Diagram | Free Wiring Diagram Collection of 3 phase transformer wiring diagram. A wiring diagram is a streamlined standard pictorial representation of an electric circuit. It shows the parts of the circuit as streamlined forms, and also the power as well as signal links between the tools.