single phase transformer impendances 2

[SNR]

If I connect three single phase transformers with an impedance of 2.5% each to form a 3 phase system what can I consider the overall impedance of the 3 phase system to be?

 

[rbulsara]

It will remain 2.5% for 3-phase system (bank of 3 transformers)as well. The %Z is a per phase value. 3-phase short circuit calculations are also done using per phase quantities.