Red Seal Electrician Practice
TransformersQuestion 1044 of 1506

Can three single-phase transformers be used to transform three-phase power?

  1. No, only a special three-phase transformer can do it
  2. Only if the three units are connected in series with each other
  3. Only when the supply is a DC supply
  4. Yes, if they are wired in a Y or delta bank
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Correct answer: Yes, if they are wired in a Y or delta bank

A special three-phase unit is lighter and smaller, but a bank of single units works with the same connections.

Source: Lessons in Electric Circuits II: AC (Kuphaldt), 7.6: Three-phase Transformer Circuits

Practice transformers

Questions last reviewed: 18 October 2026