GATE Electrical Engineering (EE) 2017 Shift 2 Solved Paper

A 3-phase, 2-pole, 50 Hz, synchronous generator has a rating 250 MVA, 0.8 pf lagging. The kinetic energy of the machine at synchronous speed is 1000 MJ. The machine is running steadily at synchronous speed and delivering 60 MW power at a power angle of 10 electrical degrees. If the load is suddenly removed, assuming the acceleration is constant for 10 cycle, the value of the power angle after 5 cycles is ________ electrical degrees.