Johnson Electric Coil Logo

What is the Difference Between a Single Phase and Three Phase Transformer?
Can Single Phase Transformers be Used for Three Phase Applications?


Systems involving single phase transformers have power lines as the input source. However, they only need one primary and one secondary winding to facilitate voltage transformation. They are available in various models with varying features in terms of mounting type, horsepower range, dimensions, taps, shipping weight, and kVA.

With systems involving three phase transformers, the power is produced by the rotation of three coils or windings through a magnetic field inside the generator. These windings are spaced hundred and 120 degrees apart and produce power as they rotate through the magnetic field. The power that is generated from this system is distributed to three separate lines, and thus identified as three phase power.

Three phase transformers can only work properly if they have three coils or windings attached in proper order to correspond with the incoming voltage. The transformer transforms the incoming voltage to the required voltage level while also retaining proper phasing and polarity.

Three Phase Industrial Applications

Three phase electricity is the best and most efficient Avenue for powering industrial loads. It can facilitate the smooth operation of heavy-duty equipment since voltage can be transmitted over long distances with the smaller conductor. If single phase power is required, two phases of the three phase system can be used to harness the power. In some situations, single phase power can be applied between the ground and only one phase.

Single phase power is:

  • Used and able to supply enough power for most residential homes and small businesses
  • Ample power supply for operating motors of 5 hp or less.

3-phase power is:

  • Efficient for equipment designed to operate on three phase power
  • Used widely in large businesses, including manufacturing industry worldwide
  • Used more often now in high density data centers
  • Allows for less expensive and smaller wiring and lower voltages, making it less expensive and safer to operate.

Single phase transformers may for three phase applications in one of the following ways:

  • Join any two wires of a three-phase source to the primary leads in order to achieve a single phase output with a single transformer.
  • Bank three individual single phase transformers for connection in either a delta-wye or delta-delta configuration to achieve a three phase output. They properly connected an equivalent three phase capacity is three times each single phase transformer’s nameplate rating

At Johnson Electric Coil Company, we are your source for custom transformer solutions, including single phase and three phase transformers. Contact us today to learn how we can serve your transformer needs.