# Three phase balanced transformer network with b-phase fault

100 kVA, 11 kV (delta) : 400 V (wye), Xeq = 0.1 p.u
with a neutral to ground connected through Zn = j0.1 (ohm)

I have a question where the above transformer is fed by a balanced positive sequence three phase source, and parallel delta and wye loads are connected on the load side of the transformer. I am then told that the b-phase drops to zero (not an open circuit).

I see they specified in the answer that there is no zero-sequence current after the fault.

Vo = 1/3(Va + Vb + Vc) Which would not be zero.

My textbook states: "In a balanced Y-connected system, line currents have no zero-sequence component, since the neutral current is zero."
But after the fault we no longer have a balanced system.

1) What is the purpose of stating that it is not an open circuit, what is the difference in this context?
2) Why is the zero-sequence current zero?
3) Does Xeq refer to the leakage reactance only?