Estimating 3 Winding Transformer %Z

[ThePunisher]

Hi all, is there like a rule of thumb on estimating %Z of 3 winding transformer based on kVA size. ETAP does not have any auto-estimate for this type but it has for two winding. We are modeling it but we have not bought it yet.

Any reference or suggestions will help. Thanks

 

[prc]

There are no general pattern for 3 winding transformers. It depends on the applications plus MVA of each circuit and general range of Z followed by the utility for 2 winding units. If you can give above details I can guestimate the values.

 

[krisys]

If you want the thumb rule, better refer IEC or IEEE and used the recommended values. Rule of thumb may not work with technically sound clients.