Question

Power consumed by a balanced 3-phase, 3-wire load is measured by two wattmeter method. The first wattmeter reads twice that of the second. Then the load impedance angle in radians is

• A. $\frac{\pi }{12}$
• B. $\frac{\pi }{8}$
• C. $\frac{\pi }{6}$
• D. $\frac{\pi }{3}$

Answer 1

The correct option is C $\frac{\pi }{6}$

$Giventhat{W}_1=2W_2$

Load impednace angle

$\varphi =ta{n}^{-1}\left[\sqrt{3}\left(\frac{W_1-W_2}{W_1+W_2}\right)\right]$

$=ta{n}^{-1}\left[\sqrt{3}\left(\frac{2W_2-W_2}{3W_2}\right)\right]$

$=\frac{\pi }{6}$