Question

In a balanced Y -Y connected 3 -phase circuit, the maximum value of line-to-line voltage is 294V and total power absorbed by the load is 500 W at a power factor of 0.6 leading. The magnitude of impedance is ________$\Omega$.

• A. 51.9

Answer 1

The correct option is A 51.9
In a Balanced three phase circuit,

Active power =$P=\sqrt{3}{V}_L{I}_{L}cos\varphi$
$500=\sqrt{3}\times \left[\frac{294}{\sqrt{2}}\right]\times I_L\times 0.6$
$I_L=\frac{500}{\sqrt{3}\times 207.89\times 0.6}=2.31\angle co{s}^{-1}\left(0.6\right)A$
$I_L=2.31\angle {53.13}^{\circ }A$
$|Z|=\frac{V_{Ph}}{I_{rms}}=\frac{\left(207.89/\sqrt{3}\right)}{2.31}$
$=51.96\Omega$