Three Winding Transformer Impedance Calculation

[volkanksr]

Hello everybody,

I need to calculate %R+ resistance and %X+ reactance values of primary-secondary, primary-tertiary and secondary-tertiary windings. Transformer information :

120/60/60 MVA
154/11/11 kV
Uk: 16%/16%/16%
Po: 40 kW
Pk: 400 kW
Io: %0.25

Please send your calculation results, formulas or any related document about this topic.

best regards,

vlk

 

[davidbeach]

Look at either of Blackburn's books, the Relay book or the Symmetrical Components book.

 

[volkanksr]

I am using these formulas . Is it right to use these ones or do you have other way to calculate these resistance and reactance values?

Zb=(Ub*Ub)/Sb where Ub:154 kV Sb:110 MVA

R1: (Psc*Un*Un)/(2.Sn*Sn) ohms
R2=R3=2R1

R1_2= R1+R2
R1_3= R1+R3
R2_3= R2+R3

R1_2(Per Unit)= R1_2/Zb

Thanks for your help

VLK