• Model Question for Electrical Machines-II

PART – A

1. Define electric motor.

2. Define electric generator.

3. Define excitation.

4. What are the methods of excitation?

5. What do you mean by self excited machine?

6. What do you mean by separately excited machine?

7. State the function of commutator.

8. What do you mean by commutation?

9. What is the purpose of brushes?

10. By which material yoke can be manufactured?

11. Why the brushes are made upon carbon?

12. What are the types of self excited generator?

13. Define shunt generator.

14. Define series generator.

15. Define compound generator.

16. Draw the open circuit characteristics of dc separately excited generator.

17. What do you mean by magnetization curve?

18. Draw the load characteristics of separately excited dc generator.

19. Draw the characteristics for DC shunt generator.

20. Draw the characteristics of DC series generator.

21. Draw the characteristics of DC compound generator.

22. What is the principle of operation of dc generator?

23. Write down faradey's law of electromagnetic induction.

24. What is the principle of operation of DC motor?

25. State lenz's law.

26. How Lenz's law is helpful for the operation of DC motor?

27. Write the significance of back e.m.f.

28. Define back e.m.f.

29. Write the e.m.f. equation of DC generator.

30. Write down the voltage equation of DC motor.

31. Write the torque equation of DC motor.

32. Draw the characteristics of DC shunt motor.

33. Draw the characteristics of DC series motor.

34. Draw the characteristics of DC compound motor.

35. Differentiate differentially compound and cumulatively compound motor.

36. What are the applications of DC shunt motor?

37. What are the applications of DC series motor?

38. What are the applications of DC compound motor?

39. Why shunt motor is called as constant speed machine?

40. Why starter is needed in DC motor?

41. What is the advantage of 4 point starter over 3 point starter?

42. State the function of no volt coil.

43. State the function of over load release.

44. What is the advantage of conducting Swin-burne's test?

45. Draw the diagram of ward-leanord system of speed control.

46. By which method, we can control the speed of the motor below the base speed?

47. By which method, the speed control of the DC motor be above the base speed?

48. What are the various methods of speed control of DC motor?

49. Differentiate armature voltage control method and field flux control method.

50. What do you mean by brake test?

PART – B

51. Explain in detail the constructional details of DC machine.

52. Derive the e.m.f. equation (8)

53. Draw and explain the characteristics of DC generator.

54. Derive the torque equation/

55. Write down the significance of back e.m.f.

56. Write down the principle of operation of DC motor.

57. Draw and explain the characteristics of DC motor.

58. Draw and explain 3 point starter.

59. What is the draw back in 3 point starter and how it is overcome in 4 point starter?

60. Explains the procedure of swin burne's test.

61. Draw and explain the speed control methods of DC shunt motor.

62. Explain in detail about the ward-leonard system of speed control of DC motor.

63. Problem.

UNIT – II

PART – A 

1. State the principle of operation of transformer.

2. What are the types of transformer according to its construction?

3. Differentiate core type transformer and shell type transformer.

4. Write down the e.m.f equation of transformer.

5. Write down the transformation ratio.

6. Define magneting current component.

7. Define working current component.

8. Draw the vector diagram of transformer an no load.

9. How the resistance of the secondary be referred in the primary?

10. Draw the approximate equivalent circuit of the transformer.

11. Draw the vector diagram for the transformer under resistive load.

12. Draw the vector diagram for the transformer under inductive load.

13. Draw the vector diagram of the transformer under comparative load.

14. When the transformer is said to be ideal?

15. Define voltage regulation of transformer.

16. Define voltage regulation up.

17. Define voltage regulation down.

18. By conducting no load test, which losses can be found out?

19. Which losses can be found out by conducting short circuit test?

20. What are the tests to be conducted on the transformer?

PART - B

1. Derive the e.m.f. equation of transformer.

2. Explain in detail about the transformer on no load.

3. Draw and explain ideal transformer. Draw its vector diagram.

4. Obtain the equivalent circuit of the transformer by conducting suitable tests.

5. Draw and explain in detail about the transformer an load.

6. Derive the regulation formula for the transformer.

7. Explain in detail about the testing procedures for the transformer.