A 3 MVA, 3 phase, 2300 V , 60 Hz, 10 poles, star-connected cylindrical-rotor synchronous motor is connected to an infinite bus. The synchronous reactance is 0.8 pu. All losses may be neglected. The synchronous motor deliver 1000 hp and the motor operates at 0.85 power factor leading.
(a) Determine the excitation voltage Ef.
(b) Determine the maximum power and torque the motor can deliver for the excitation current of part (a)
(c) The power output is kept constant at 1000 hp  and the field current is decreased. By what factor can the field current of part (a) be reduced before synchronism is lost?

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