A star-connected 8 poles, 50 Hz, synchronous motor has synchronous reactance of 11 W per phase. On no-load, both the excitation and the terminal voltages are equal to 3.3 kV. Neglect all losses.
For a sudden disturbance in the shaft-load torque, the rotor falls back in space by one mechanical degree. Calculate the synchronising current, synchronising power and synchronising torque tending to restore the rotor to its previous position.
With gradual increase in the shaft load, the rotor slides back in space by one mechanical degree. Calculate the armature current. For an armature current of 30 A, find the angle in mechanical degrees, through which the rotor slips back.