A 50-Hz generator, connected directly to an infinite bus operating at a voltage of 1∠0° pu, has a synchronous reactance of 1.35 pu. The generator no-load voltage is 1.1 pu, and its inertia constant H is 4 MJ/MVA. The generator is suddenly loaded to 60 percent of its maximum power limit. Determine the frequency of the resulting natural oscillations of the generator rotor.
[Ans. 0.805 Hz]