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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:

Specs

And the fields which need to be populated:

Values

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  • \$\begingroup\$ A reasonable assumption is that Z0 is about 85% of Z1. \$\endgroup\$ – Li-aung Yip Aug 7 '14 at 13:05
  • \$\begingroup\$ On further inspection, this appears to be a wye-wye transformer with buried delta tertiary. The above comment I made a year ago isn't really accurate for this case. Try reading some of the references I have cited in electronics.stackexchange.com/questions/195239/… . \$\endgroup\$ – Li-aung Yip Oct 14 '15 at 15:40
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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)

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