Question 1 of 56

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

Carbon and graphite

Aluminium and graphite

Cast iron and graphite

Steel and graphite

Question 1 of 56

Question 2 of 56

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

Increased output voltage

Pulsating output voltage

Decreased output voltage

Zero output voltage

Question 2 of 56

Question 3 of 56

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

Low current, low voltage

Low current, high voltage

High current, low voltage

High current, high voltage

Question 3 of 56

Question 4 of 56

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

Minimize rough commutation

Decrease field coil excitation current

Maintain constant output voltage

Neutralize demagnetizing effect

Question 4 of 56

Question 5 of 56

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

Excessive brush spring tension

Shift in MNA and GNA positions

Short circuit in field winding

Short circuit in armature winding

Question 5 of 56

Question 6 of 56

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

Fleming’s left hand rule

Right hand palm rule

Cork screw rule

Fleming’s right hand rule

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Question 7 of 56

7. 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 7 of 56

Question 8 of 56

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

Increase air gap flux

Reduce magnetizing current

Magnetize poles to produce flux

Increase magnetic path reluctance

Question 8 of 56

Question 9 of 56

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

Minimize magnetic losses

Spread flux uniformly in the air gap

Increase field strength

Reduce air gap

Question 9 of 56

Question 10 of 56

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

Reduce friction loss

Reduce eddy current loss

Reduce hysteresis loss

Reduce windage loss

Question 10 of 56

Question 11 of 56

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

Heat energy

Kinetic energy

Chemical energy

Mechanical energy

Question 11 of 56

Question 12 of 56

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

Resistance wires in windings

Compensating winding

Increased brush contact resistance

Additional interpoles

Question 12 of 56

Question 13 of 56

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

Field coil resistance increases

Armature resistance increases

Loss of residual magnetism

Increased armature reaction

Question 13 of 56

Question 14 of 56

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

Continuous no-load running

Uninterrupted operation

Heavy short circuit in load

Frequent direction changes of rotation

Question 14 of 56

Question 15 of 56

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

Direct current voltage

Oscillating voltage

Alternating voltage

Pulsating voltage

Question 15 of 56

Question 16 of 56

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

Laminated pole core

Field coils

Armature winding conductors

Armature core

Question 16 of 56

Question 17 of 56

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

Series generator

Separately excited generator

Compound generator

Shunt generator

Question 17 of 56

Question 18 of 56

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

Shunt field voltage drop

Full load voltage drop

Armature voltage drop

Armature reaction drop

Question 18 of 56

Question 19 of 56

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

B

C

D

A

Question 19 of 56

Question 20 of 56

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

Cumulative compound generator

Series generator

Differential compound generator

Shunt generator

Question 20 of 56

Question 21 of 56

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

Shunt generator

Compound generator

Series generator

Self-excited generator

Question 21 of 56

Question 22 of 56

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

Side end plates

Pole shoe lamination

Armature core lamination

Commutator segment

Question 22 of 56

Question 23 of 56

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

Pole shoe

Pole coil

Pole core

Pole tip

Question 23 of 56

Question 24 of 56

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

6

12

4

8

Question 24 of 56

Question 25 of 56

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

Reduce temperature of armature

Reduce armature voltage drop

Run armature with less weight

Reduce armature current

Question 25 of 56

Question 26 of 56

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

Neutralize armature reaction effect

Reduce commutation effect

Connect more loads

Increase generator efficiency

Question 26 of 56

Question 27 of 56

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

Pulsating output voltage

Normal voltage buildup

Above-normal output voltage

Voltage buildup failure

Question 27 of 56

Question 28 of 56

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

Differential short shunt compound

Differential long shunt compound

Cumulative short shunt compound

Cumulative long shunt compound

Question 28 of 56

Question 29 of 56

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

480 V

160 V

320 V

640 V

Question 29 of 56

Question 30 of 56

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

Commutator segment

Brush

Armature core

Commutator riser

Question 30 of 56

Question 31 of 56

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

Cumulative compound generator

Differential compound generator

Long shunt compound generator

Short shunt compound generator

Question 31 of 56

Question 32 of 56

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

Shunt generator

Series generator

Differential compound generator

Cumulative compound generator

Question 32 of 56

Question 33 of 56

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

Field resistance above critical value

High armature resistance

Prime mover running above rated speed

Loose brush contact

Question 33 of 56

Question 34 of 56

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

Increase residual magnetism

Reduce copper loss

Reduce magnetic path reluctance

Decrease residual magnetism

Question 34 of 56

Question 35 of 56

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

Protect brushes from damage

Avoid generator overloading

Protect residual magnetism

Avoid short circuit in armature

Question 35 of 56

Question 36 of 56

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

Cast iron

Stainless steel

Cast steel

Soft iron

Question 36 of 56

Question 37 of 56

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

In parallel with the shunt field

In parallel with the armature

In series with the shunt field

In series with the armature

Question 37 of 56

Question 38 of 56

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

Soft iron

Aluminium

Rolled steel

Cast iron

Question 38 of 56

Question 39 of 56

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

Regular commutator cleaning

Blowing hot air during maintenance

Periodic machine heating

Frequent brush replacement

Question 39 of 56

Question 40 of 56

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

Stator

Pole core

Pole shoes

Yoke (or frame)

Question 40 of 56

Question 41 of 56

41. 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

243 V

428 V

357 V

Question 41 of 56

Question 42 of 56

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

Armature reaction effect

Increased armature resistance

Increased shunt field inductance

Reduced brush voltage drop

Question 42 of 56

Question 43 of 56

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

EMF becomes zero

EMF increases

EMF decreases

No change in EMF

Question 43 of 56

Question 44 of 56

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

Smooth current direction reversal

Nullify statically induced EMF

Maintain constant voltage

Increase statically induced EMF

Question 44 of 56

Question 45 of 56

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

To reduce armature current

To build up the voltage

To reduce the field current

To maintain constant output voltage

Question 45 of 56

Question 46 of 56

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

BLV volts

BL sinθ volts

BLV cosθ volts

BLV sinθ volts

Question 46 of 56

Question 47 of 56

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

D

A

B

C

Question 47 of 56

Question 48 of 56

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

Differential compound generator

Series generator

Cumulative compound generator

Shunt generator

Question 48 of 56

Question 49 of 56

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

Easy shaft removal

Fix the keyway

Enable air circulation

Lubrication

Question 49 of 56

Question 50 of 56

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

Cork screw rule

Fleming's right hand rule

Right hand palm rule

Fleming's left hand rule

Question 50 of 56

Question 51 of 56

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

Cork screw rule

Fleming’s right hand rule

Fleming’s left hand rule

Faraday’s laws of electromagnetic induction

Question 51 of 56

Question 52 of 56

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

Series generator

Separately excited generator

Compound generator

Shunt generator

Question 52 of 56

Question 53 of 56

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

Reduce hysteresis loss

Reduce friction loss

Reduce copper loss

Reduce eddy current loss

Question 53 of 56

Question 54 of 56

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

Resistance between the opposite brushes

Resistance between brush and commutator riser

Resistance between brush and commutator

Resistance between brush and armature conductors

Question 54 of 56

Question 55 of 56

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

Increase terminal voltage beyond rated

Collect current unidirectionally

Maintain constant voltage

Reduce voltage drop at brushes

Question 55 of 56

Question 56 of 56

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

Differential compound

Cumulative compound

Long shunt compound

Short shunt compound

Question 56 of 56