Star – Star Connection Overview

Since the secondary could also be connected either in Y or Δ in spite of that association is employed on the primaries, there should be four ways that of connecting the windings of a 3-phase electrical device for the transformation of 3-phase voltages, namely Y-y, Δ -Δ, Y-Δ, and Δ -y.

The inter-connections are made inside of the case so that only the terminal leads need to be brought outside the case:


  1. (Grounding Transformer)
  2. Delta – Star Transformer (Dy)
  3. Star – Delta Transformer (Yd)
  4. Star – Star Transformer (Yy0 or Yy6)
  5. Delta – Delta Transformer (Dd0 or Dd6)
  6. Zig-zag Transformer (Yz, Dz) (Grounding Transformer)
  7. Scott (“T” Type) Transformer (Grounding Transformer)

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