Zero-sequence capacitance of power transformer

[ypo]

To make the ground fault calculations for our system I need the zero-sequence capacitance per phase of the power transformer.
The power transformer is 3 MVA, step-up, D/Y, 4.16kv/25kv, impedance 5%.
Us the manufacturer can not give me this value (this range of transformers being to small to perform such kind of tests, so no historical; our transformer still in construction) I'm looking for some tables, or curves, or standards from which I can deduct the needed value.
Can someone give me a tip.

 

[rbulsara]

Never heard of needing zero seq capacitance to calculate GFC for a transformer!

 

[jbartos]

Suggestion: Reference:
1. IEEE Std 399-1997 IEEE Recommended Practice for Industrial and Commercial Power System Analysis, (Brown Book)
Figure 11-34 Typical Values of Transformer Winding Capacitance to Ground, page 371.
The capacitance is a parametric function of BIL
e.g. A-110 BIL 1500picofarads/phase for 1MVA of transformer rating per phase, i.e. 3MVA/3phase=1MVA/phase
B-150 BIL 2000picofarads per phase, for 1MVA
C-200 BIL 2250picofarads per phase, for 1MVA
etc.

 

[ypo]

rbulsara, I need it to size the Neutral grounding transformer and resistor.

jbartos, thank you!