#1. A 6-pole alternator rotates at 1000 rpm. The generated frequency is:
Solution: f = (P * Ns) / 120 = (6 * 1000) / 120 = 50 Hz
#2. The generated EMF in an alternator depends on:
#3. If the flux per pole in an alternator is doubled, the generated EMF will:
Solution: Eg is directly proportional to flux.
#4. The distribution factor accounts for:
- Answer: a) The spread of the winding. Solution: The distribution factor considers how the conductors are distributed in the slots.
#5. A short-pitched coil has a pitch factor:
- Solution: Short pitched coils have a coil span less than 180 electrical degrees.
#6. The voltage regulation of an alternator is defined as:
#7. A good alternator should have voltage regulation:
- Answer: b) Low. Solution: Lower voltage regulation means a more stable output voltage.
#8. The power output of a synchronous generator is given by:
#9. A lagging power factor load on an alternator requires:
#10. Synchronous impedance is composed of:
#11. The synchronous impedance of an alternator can be determined by:
#12. During parallel operation, real power sharing is controlled by:
#13. Armature reaction in a synchronous generator primarily affects:
- Solution: Armature reaction modifies the main field, thus affecting the voltage.
#14. In a synchronous generator supplying a lagging power factor load, the armature reaction is:
Solution: Lagging p.f. loads cause a demagnetizing effect.
#15. Increasing the excitation of a synchronous generator connected to an infinite busbar leads to:
#16. Over-excitation of a synchronous generator can lead to:
#17. The open-circuit characteristic (OCC) of a synchronous generator shows the relationship between:
#18. The short-circuit characteristic (SCC) of a synchronous generator shows the relationship between:
#19. Salient pole rotors are generally used in:
#20. Cylindrical rotors are generally used in:
#21. Which of the following is a common cooling method for large synchronous generators?
#22. Hydrogen cooling is preferred for large generators because of its:
#23. Synchronous generators are primarily used in:
#24. A synchroscope is used to indicate:
#25. The equivalent circuit of a synchronous generator is used to analyze its:
#26. In the equivalent circuit, the generated EMF (Eg) is represented as
#27. The power angle (δ) in a synchronous generator represents the angle between:
#28. The maximum power output of a synchronous generator is reached when the power angle is approximately:
#29. The governor of a synchronous generator controls its:
#30. A change in the governor setting primarily affects the:
#31. The excitation of a synchronous generator controls its:
#32. A change in the excitation primarily affects the:
#33. Which of the following are common losses in a synchronous generator?
#34. Stray load losses in a synchronous generator are due to:
#35. In the lamp method of synchronization, the lamps are connected:
#36. Hunting in synchronous machines refers to:
#37. Hunting can be caused by:
#38. The open-circuit test on a synchronous generator is performed to determine:
#39. The short-circuit test on a synchronous generator is performed to determine:
#40. When two or more synchronous generators operate in parallel, the total load is shared based on their:
Answer: d) Governor characteristics. (Specifically, the droop characteristics of the governors.)
