Question

A generator operating at 50 Hz delivering 50 % of maximum power to an infinite bus through a transmission line. Suddenly, a short circuit occurs, and power is reduced to zero. The critical clearing angle is ________degree (Give answer upto 3 decimals).

• A. 79.562

Answer 1

The correct option is A 79.562


$P_m=P_{max}sin{\delta }_0$
$sin{\delta }_0=0.5$

${\delta }_0={30}^{\circ }or\frac{\pi }{6}rad$

$and{\delta }_{max}=\pi -{\delta }_0=\pi -\frac{\pi }{6}=\frac{5\pi }{6}rador{150}^{\circ }$

$cos{\delta }_{cr}=\frac{P_m}{P_{max}}({\delta }_{max}-{\delta }_0)+cos{\delta }_{max}=\frac{0.5}{1}(\frac{5\pi }{6}-\frac{\pi }{6})+cos\left({150}^{\circ }\right)$

The critial clearning angle,

${\delta }_{cr}=co{s}^{-1}\left(0.18117\right)={79.562}^{\circ }$