Consider the system in which a generator is connected to an infinite bus through a double circuit transmission line as shown in Fig. 9.5. The per unit system reactances that are converted in a common base, are also shown in this figure. Let us assume that the infinite bus voltage is 1< 0°. The generator is delivering 1.0 per unit real power at a lagging power factor of 0.9839 to the infinite bus. While the generator is operating in steady state, a three-phase bolted short circuit occurs in the transmission line connecting buses 2 and 4 - very near to bus 4. The fault is cleared by opening the circuit breakers at the two ends of this line. We have to find the critical clearing time for various values of H. ELS j0.3 j0.1 j0.1 j0.2 j0.1 120°