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### EEE :: Synchronous Generator

1. A three phase alternator has a phase sequence of RYB for its three output voltages. In case the field current is reversed, the phase sequence will become
2.  A. RBY B. RYB C. YRB D. none of the above

3. Two-alternators are running in parallel. If the driving force of both the alternators is changed, this will result in change is
4.  A. frequency B. back emf C. generated voltage D. all of the above

5. When two alternators are running in parallel, their RKVA load share is changed by changing their ................ while their kW load share is changed by changing their ..............
6.  A. excitation, driving torque B. driving torque, excitation C. excitation, excitation D. driving torque, driving torque

7. In order that two alternators be put in parallel, which of the following factors should be identical for both ?
8.  A. Voltage B. Frequency C. Phase sequence D. All of the above

9. Voltage characteristic of an alternator is shown in figure. Which curve represents the characteristics for leading power factor ?

10.  A. A B. B C. C D. D

11. In the above figure, the characteristic for unity power factor is represented by the curve maked
12.  A. A B. B C. C D. D

13. For 50 Hz system the maximum speed of an alternator can be
14.  A. approximately 3600 rpm B. approximately 3000 rpm C. 3600 rpm D. 3000 rpm

15. If the input of the prime mover of an alternator is kept constant but the excitation is changed, then
16.  A. the active component of the output is changed B. the reactive component of the output is changed C. power factor of the load remains constant D. power factor of the load changes from lagging to leading

17. The driving power from the prime mover driving the alternator is lost but the alternator remains connected to the supply network and the field supply also remains on. The alternator will
18.  A. get burnt B. behave as an induction motor but will rotate in the opposite direction C. behave as a synchronous motor and will rotate in the same direction D. behave as a synchronous motor but will rotate in a reverse direction to that corresponding to generator action

19. For an alternator when the power factor of the load is unity
20.  A. the armature flux will have square waveform B. the armature flux will be demagnetising C. the armature flux will be cross-magnetising D. the armature flux will reduce to zero