[PDF] Buck-Boost Transformer Installation Sheet Buck-Boost Transformer Installation Sheet Revised on April, 2011 by T.E. If you are using this unit as an isolation transformer with a primary of 120 or 240 or 480 volts and the secondary of 12/24, 16/32, or 24/48 (depending on the model) use the wiring diagram located on the inside of the cover to the wiring 480v to 240v Transformer Wiring Diagram | Free Wiring Diagram 480v to 240v Transformer Wiring Diagram - Collections Of 480 Volt to 120 Volt Transformer Wiring Diagram Image. 480v 3 Phase Transformer Wiring Diagram Step Down Tags to 120v. Step Down Transformer 480v 120v Wiring Diagram Trusted Wiring. 480v to 120v Transformer Wiring Diagram Elegant 3 Phase Step Down. Three Phase Transformer Connections and Basics Where: V L is the line-to-line voltage, and V P is the phase-to-neutral voltage. 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 Three Phase Transformer Configuration.