Resistance Model of Two-Winding Transformer

[ePOWEReng]

Hello!

I am working for a utility modeling the two winding substation transformers (generally 115kV Delta-13.8kV Wye-ground on our system). We have test reports for all of these transformers and in the past we have used the resistance from the test report in our transform models. It has been suggested by an engineer here that we should calculate the resistance using --

[Losses, Full Load] - [Losses, No load] = [Losses, Series]

And then, R = [Losses, Series] / [Current]^2

Does anybody have experience with the best way of modeling these types of transformers series resistance and reactance??

Thanks for the help.

 

[dpc]

I'd use the resistance from the test report.

If you calculate the resistance from the losses, I believe a portion of the calculated resistance will actually be due to the eddy-current losses and not the actual resistance in the windings.