2. (a) The moment of inertia of the rotating parts of a 3-phase, 2-pole, 50 Hz turbo- generator is 61,000 kg.m? (i) Calc

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2 A The Moment Of Inertia Of The Rotating Parts Of A 3 Phase 2 Pole 50 Hz Turbo Generator Is 61 000 Kg M I Calc 1 (168.74 KiB) Viewed 103 times

2. (a) The moment of inertia of the rotating parts of a 3-phase, 2-pole, 50 Hz turbo- generator is 61,000 kg.m? (i) Calculate the H constant of the machine when it supplies a rated power of 880 MW at a lagging power-factor of 0.8. [2 marks] (ii) The machine is operating in the steady-state while supplying 400 MW at a load-angle of 10°, so that do / dt = 0. A 3-phase solid short-circuit fault occurs at the machine terminals. Determine the load angle of the machine three cycles after the short-circuit fault occurs. Assume that the swing equation is taken as d²8 Male = Pm – Pe - dt2 where M = angular momentum = Jo J = moment of inertia of rotating parts 0 = synchronous speed 8 = load angle Pm = mechanical power input Pe = electrical power output. [6 marks) (iii) Use a sketch to indicate how a graph of d against time, following the occurrence of a fault, can be used as a predictor of machine instability. [2 marks]