Power Transformer Test

In 132/13.8 kv, 50 MVA, 22.17% impedance, Dyn1 power transformer, How mcuh voltage i can inject maximum to find the zero sequence impedance?

In short circuit test, the secondary sc current is 15A approx (by injecting a 3p 220v at HV side).

for zero seq imp test, can i inject the voltage upto the point where the current equals to the sc current?

Is it correct, that consider the SC current as a reference for zero seq imp current measurement?

Anybody kindly clarify, please.