Consider the synchronous generator-motor set of Ex. 8.7 whose data are repeated below.
(a) The set is operating at rated terminal voltage and frequency with the motor drawing 800 kW at upf Compute the excitation emfs of both the machines.
With the excitation emfs held fixed at these values, what maximum torque can the motor supply? Also determine the armature current, terminal, voltage and power factor under this condition.
(b) The motor shaft load is now gradually increased while the field currents of both the generator and motor are continuously adjusted so as to maintain the rated terminal voltage and upf operation. What maximum torque can the motor now deliver without losing synchronism?
Ex. 8.7:
resistance is negligible. How would the torque angle be affected by the following changes?
(a) The load torque and terminal voltage remaining constant, the excitation and frequency are raised by 10%.
(b) The load power and terminal voltage remaining constant, the excitation and frequency are reduced by 10%.
(c) The load torque and excitation remaining constant, the terminal voltage and frequency are raised by 10%.
(d) The load power and excitation remaining constant, the terminal voltage and frequency are reduced by 10%.