A generator feeds power to an infinite bus through a double circuit transmission line. A 3 phase fault occurs at the middle point of one of the lines. The infinite bus voltage is 1 pu., the transient internal voltage of the generator is 1.1 pu. & the equivalent transfer admittance during fault is 0.8 pu. The 100 MVA generator has an inertia constant of 5 MJ/MVA & it was delivering 1 pu power prior to the fault with rotor power angle of 30°. The system frequency is 50 Hz.   
If the initial accelerating power is X pu, the initial acceleration in , and the inertia constant in MJ-sec/select deg respectively will be