Question

In the above network, the marked parameters are per unit impedances. Calculate $Y_{22}$ in the bus admittance matrix

• A. +j15
• B. -j17.5
• C. +j17.5
• D. -j15

Answer 1

The correct option is B -j17.5

$Z_{11}=j0.3$
$Z_{12}=j0.1$
$Z_{22}=j0.4$
$Z_{23}=j0.2$
$Z_{33}=j0.5$
$y_{22}=y_{21}+y_{22}+y_{23}=\frac{1}{j0.1}+\frac{1}{j0.4}+\frac{1}{j0.2}$
$=-j10+(-j2.5)+(-j5)=-j17.5$