Question

A 3-phase power system is represented by one line diagram as shown in the figure below:



The ratings of equipments are the following:
Genrator (G) : 15 MVA, 6.6 kV, $X_1$ = 15%,
$X_2$ = 10%
Transformer : 15 MVA, 6.6 kV delta/33 kV star,
$X_1=X_2=X_0=6$%
Line reactance : $X_1=X_2=2\Omega and{X}_0=6\Omega$
If a SLG fault occurs on bus bar B, then the fault current is _______ p.u.

• A. 0

Answer 1

The correct option is A 0
The zero sequence network of the system is,



$X_0$ is infinite because of open circuit to the fault, so fault current is zero