Question 1 of 56

1. 8. Which type of energy is converted into electrical energy by a generator?

Chemical energy

Kinetic energy

Heat energy

Mechanical energy

Question 1 of 56

Question 2 of 56

2. 25. What is the reason a DC generator fails to build up voltage?

High armature resistance

Field resistance above critical value

Prime mover running above rated speed

Loose brush contact

Question 2 of 56

Question 3 of 56

3. 52. How is armature reaction neutralized in large DC generators?

Resistance wires in windings

Compensating winding

Increased brush contact resistance

Additional interpoles

Question 3 of 56

Question 4 of 56

4. 18. Which two points measure the brush contact resistance in DC machines?

Resistance between brush and commutator riser

Resistance between brush and commutator

Resistance between brush and armature conductors

Resistance between the opposite brushes

Question 4 of 56

Question 5 of 56

5. 19. Which voltage drop is indicated in the portion marked as 'X' in a DC generator?

Full load voltage drop

Armature voltage drop

Armature reaction drop

Shunt field voltage drop

Question 5 of 56

Question 6 of 56

6. 17. What is the necessity of residual magnetism in a self-excited DC generator?

To reduce armature current

To maintain constant output voltage

To reduce the field current

To build up the voltage

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Question 7 of 56

7. 16. How are interpoles connected in a DC generator?

In series with the shunt field

In series with the armature

In parallel with the armature

In parallel with the shunt field

Question 7 of 56

Question 8 of 56

8. 31. How does the magnetic circuit complete through the yoke and poles in a generator?

Armature winding conductors

Laminated pole core

Field coils

Armature core

Question 8 of 56

Question 9 of 56

9. 11. What is the formula for dynamically induced emf?

BL sinθ volts

BLV volts

BLV cosθ volts

BLV sinθ volts

Question 9 of 56

Question 10 of 56

10. 15. Name the part of a DC generator that consists of thin laminated sheets to reduce eddy currents.

Armature core lamination

Side end plates

Pole shoe lamination

Commutator segment

Question 10 of 56

Question 11 of 56

11. 34. Which method improves insulation resistance in DC generators?

Frequent brush replacement

Regular commutator cleaning

Blowing hot air during maintenance

Periodic machine heating

Question 11 of 56

Question 12 of 56

12. 20. What is the name of the compound generator if the shunt field is connected in parallel with the armature?

Differential compound

Cumulative compound

Short shunt compound

Long shunt compound

Question 12 of 56

Question 13 of 56

13. 14. How many parallel paths are there in a duplex lap winding of a 4-pole DC generator?

8

6

4

12

Question 13 of 56

Question 14 of 56

14. 26. What is the name of the generator if its field is connected in parallel with the armature?

Series generator

Compound generator

Shunt generator

Self-excited generator

Question 14 of 56

Question 15 of 56

15. 40. Which metal is used for large-capacity DC generator yokes?

Aluminium

Cast iron

Soft iron

Rolled steel

Question 15 of 56

Question 16 of 56

16. 42. Which voltage is induced dynamically in a DC generator?

Pulsating voltage

Alternating voltage

Direct current voltage

Oscillating voltage

Question 16 of 56

Question 17 of 56

17. 29. Which material is used to make brushes in generators?

Cast iron and graphite

Carbon and graphite

Steel and graphite

Aluminium and graphite

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Question 18 of 56

18. 23. Why should a DC generator run only in the clockwise direction?

Protect residual magnetism

Avoid short circuit in armature

Protect brushes from damage

Avoid generator overloading

Question 18 of 56

Question 19 of 56

19. What is the name of the DC generator described as having cumulative short shunt compounding?

Differential long shunt compound

Cumulative long shunt compound

Cumulative short shunt compound

Differential short shunt compound

Question 19 of 56

Question 20 of 56

20. 21. Why is the armature core of a DC generator laminated?

Reduce hysteresis loss

Reduce eddy current loss

Reduce friction loss

Reduce copper loss

Question 20 of 56

Question 21 of 56

21. 56. What causes heavy sparking in DC generator brushes?

Short circuit in armature winding

Short circuit in field winding

Shift in MNA and GNA positions

Excessive brush spring tension

Question 21 of 56

Question 22 of 56

22. 49. What happens if shunt field resistance exceeds critical value in a DC generator?

Pulsating output voltage

Voltage buildup failure

Above-normal output voltage

Normal voltage buildup

Question 22 of 56

Question 23 of 56

23. 44. What is the purpose of field coils in a DC generator?

Increase magnetic path reluctance

Magnetize poles to produce flux

Reduce magnetizing current

Increase air gap flux

Question 23 of 56

Question 24 of 56

24. 46. Why are pole core stampings laminated in DC generators?

Reduce eddy current loss

Reduce hysteresis loss

Reduce windage loss

Reduce friction loss

Question 24 of 56

Question 25 of 56

25. 35. Which DC generator works without residual magnetism?

Separately excited generator

Series generator

Shunt generator

Compound generator

Question 25 of 56

Question 26 of 56

26. 53. What happens if a DC generator is idle for a long time?

Loss of residual magnetism

Increased armature reaction

Armature resistance increases

Field coil resistance increases

Question 26 of 56

Question 27 of 56

27. 43. What is the purpose of the slot marked 'X' in a DC generator?

Lubrication

Fix the keyway

Enable air circulation

Easy shaft removal

Question 27 of 56

Question 28 of 56

28. 10. What is the principle of a DC generator?

Fleming’s right hand rule

Fleming’s left hand rule

Cork screw rule

Faraday’s laws of electromagnetic induction

Question 28 of 56

Question 29 of 56

29. 5. What is the formula to calculate back emf of a DC motor?

A

B

D

C

Question 29 of 56

Question 30 of 56

30. 7. What is the name of the DC generator that requires separate excitation?

Compound generator

Series generator

Separately excited generator

Shunt generator

Question 30 of 56

Question 31 of 56

31. 22. Why is the armature resistance of a DC generator kept very low?

Reduce armature current

Run armature with less weight

Reduce armature voltage drop

Reduce temperature of armature

Question 31 of 56

Question 32 of 56

32. 4. Which formula is used to calculate the generated emf in a DC generator?

C

D

A

B

Question 32 of 56

Question 33 of 56

33. 28. What is the function of split rings in a DC generator?

Reduce voltage drop at brushes

Maintain constant voltage

Increase terminal voltage beyond rated

Collect current unidirectionally

Question 33 of 56

Question 34 of 56

34. 30. Why do DC generators lose residual magnetism?

Heavy short circuit in load

Continuous no-load running

Frequent direction changes of rotation

Uninterrupted operation

Question 34 of 56

Question 35 of 56

35. 1. What is the name of the part marked as 'X' in a DC generator?

Commutator segment

Commutator riser

Armature core

Brush

Question 35 of 56

Question 36 of 56

36. 41. What is the function of split rings in a DC generator?

Continuous output supply

Unidirectional output

Opposite direction output

Collect output from alternate conductors

Question 36 of 56

Question 37 of 56

37. 51. Calculate the EMF generated in a 4-pole, simplex wave-wound DC generator with 1020 conductors at 1500 rpm and 0.007 Wb flux/pole.

178 V

428 V

243 V

357 V

Question 37 of 56

Question 38 of 56

38. 32. Why does terminal voltage decrease with increased load in a DC shunt generator?

Increased shunt field inductance

Reduced brush voltage drop

Increased armature resistance

Armature reaction effect

Question 38 of 56

Question 39 of 56

39. 37. What is the property of wave winding in DC generators?

Low current, low voltage

High current, high voltage

High current, low voltage

Low current, high voltage

Question 39 of 56

Question 40 of 56

40. 3. Which rule is used to find the direction of induced emf in a DC generator?

Right hand palm rule

Cork screw rule

Fleming's left hand rule

Fleming's right hand rule

Question 40 of 56

Question 41 of 56

41. 55. What happens to induced EMF if main field flux distorts in a DC generator?

EMF decreases

EMF increases

No change in EMF

EMF becomes zero

Question 41 of 56

Question 42 of 56

42. 9. What is the name of the DC generator's field where the series field opposes the shunt field?

Differential compound generator

Long shunt compound generator

Short shunt compound generator

Cumulative compound generator

Question 42 of 56

Question 43 of 56

43. 45. Which metal is used for pole cores in large DC generators?

Cast iron

Cast steel

Stainless steel

Soft iron

Question 43 of 56

Question 44 of 56

44. 6. What is the name of the part marked 'X' in a DC generator (pole assembly)?

Pole core

Pole shoe

Pole tip

Pole coil

Question 44 of 56

Question 45 of 56

45. 36. Which DC generator is used for arc welding?

Differential compound generator

Cumulative compound generator

Shunt generator

Series generator

Question 45 of 56

Question 46 of 56

46. 27. What is the purpose of pole shoes in a DC generator?

Minimize magnetic losses

Increase field strength

Spread flux uniformly in the air gap

Reduce air gap

Question 46 of 56

Question 47 of 56

47. 39. Why are solid pole shoes used in DC generators?

Decrease residual magnetism

Increase residual magnetism

Reduce magnetic path reluctance

Reduce copper loss

Question 47 of 56

Question 48 of 56

48. 13. What is the name of the part of a DC generator that provides mechanical support and a path for magnetic flux?

Pole shoes

Pole core

Stator

Yoke (or frame)

Question 48 of 56

Question 49 of 56

49. 47. Which DC generator is used for electroplating?

Shunt generator

Series generator

Cumulative compound generator

Differential compound generator

Question 49 of 56

Question 50 of 56

50. 50. What is the effect of armature reaction in DC generators?

Decreased output voltage

Zero output voltage

Pulsating output voltage

Increased output voltage

Question 50 of 56

Question 51 of 56

51. 38. What is the purpose of resistance wire in commutator connections?

Increase statically induced EMF

Maintain constant voltage

Smooth current direction reversal

Nullify statically induced EMF

Question 51 of 56

Question 52 of 56

52. 24. Why is compensating winding provided in large DC generators?

Neutralize armature reaction effect

Increase generator efficiency

Reduce commutation effect

Connect more loads

Question 52 of 56

Question 53 of 56

53. 48. What is the purpose of compensating winding in DC generators?

Neutralize demagnetizing effect

Maintain constant output voltage

Minimize rough commutation

Decrease field coil excitation current

Question 53 of 56

Question 54 of 56

54. 54. Calculate the induced EMF of a 4-pole, lap-wound dynamo at 1000 rpm with 600 conductors and 0.064 Wb flux/pole.

320 V

480 V

160 V

640 V

Question 54 of 56

Question 55 of 56

55. 33. Which DC generator is used for long-distance distribution lines?

Series generator

Cumulative compound generator

Shunt generator

Differential compound generator

Question 55 of 56

Question 56 of 56

56. 12. Which rule is used to find the direction of a magnetic field?

Right hand palm rule

Fleming’s right hand rule

Cork screw rule

Fleming’s left hand rule

Question 56 of 56