Electronic – Typical zero sequence data for 80MVA transformer


I need to model a 80MVA transformer 132/33kV built in 1973. There is very little information on this transformer but I need to populate certain values in the model.

Where can I find typical zero sequence impedance values for this type of transformer?

The positive sequence impedances are as follows:

  • HV – MV = 15%
  • HV – LV = 22.9%
  • MV – LV = 4.9%

Here is the information given:


And the fields which need to be populated:


Best Answer

usually the 132/33kv transformers have a Y / D connection and th LV side is resistance grounded through zig-zag transformer and so they have a moderate zero sequense impedance. but some tests show that,

The zero-sequence impedance is usually given as a percentage of the rated phase impedance.

When the transformer has a three-limb core and no delta-connecter windings, the zero-sequence impedance is about 30...60 %. When the transformer has a delta-connected winding, the zero-sequence impedance is 0.8...1.0 times the corresponding short-circuit impedance (uk%).

(from Testing of Power Transformer – Measurement of Zero-Sequence Impedance)