Question

A generator is connected to a transformer which feeds another transformer through a short feeder. The zero-sequence impedance values are expressed in p.u. on a common base and are indicated in figure below



The Thevenin's equivalent of zero sequence impedance at P is

• A. (1.5 + j 0.25) p.u.
• B. (0.6 + j0.16) p.u.
• C. (0.8 + j 0.6)p.u.
• D. (0.75 + j0.22) p.u.

Answer 1

The correct option is B (0.6 + j0.16) p.u.

The zero sequence impedance network from point P and ground


the Thevenin's equivalent zero sequence impedance
$Z_{Th}=(0.6+j0.16)p.u.$