Question 1 of 56

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

4

6

8

12

Question 1 of 56

Question 2 of 56

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

Pulsating voltage

Alternating voltage

Direct current voltage

Oscillating voltage

Question 2 of 56

Question 3 of 56

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

Cast iron

Stainless steel

Soft iron

Cast steel

Question 3 of 56

Question 4 of 56

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

Series generator

Cumulative compound generator

Differential compound generator

Shunt generator

Question 4 of 56

Question 5 of 56

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

Continuous no-load running

Heavy short circuit in load

Uninterrupted operation

Frequent direction changes of rotation

Question 5 of 56

Question 6 of 56

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

B

A

D

C

Question 6 of 56

Question 7 of 56

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

Loose brush contact

Prime mover running above rated speed

Field resistance above critical value

High armature resistance

Question 7 of 56

Question 8 of 56

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

Self-excited generator

Series generator

Compound generator

Shunt generator

Question 8 of 56

Question 9 of 56

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

Reduce commutation effect

Neutralize armature reaction effect

Increase generator efficiency

Connect more loads

Question 9 of 56

Question 10 of 56

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

Neutralize demagnetizing effect

Minimize rough commutation

Decrease field coil excitation current

Maintain constant output voltage

Question 10 of 56

Question 11 of 56

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

Cumulative compound

Long shunt compound

Short shunt compound

Differential compound

Question 11 of 56

Question 12 of 56

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

Armature reaction drop

Armature voltage drop

Full load voltage drop

Shunt field voltage drop

Question 12 of 56

Question 13 of 56

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

Steel and graphite

Cast iron and graphite

Aluminium and graphite

Carbon and graphite

Question 13 of 56

Question 14 of 56

14. 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 14 of 56

Question 15 of 56

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

In series with the shunt field

In parallel with the armature

In series with the armature

In parallel with the shunt field

Question 15 of 56

Question 16 of 56

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

Decrease residual magnetism

Reduce copper loss

Increase residual magnetism

Reduce magnetic path reluctance

Question 16 of 56

Question 17 of 56

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

Protect brushes from damage

Avoid short circuit in armature

Avoid generator overloading

Protect residual magnetism

Question 17 of 56

Question 18 of 56

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

Pulsating output voltage

Normal voltage buildup

Voltage buildup failure

Above-normal output voltage

Question 18 of 56

Question 19 of 56

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

Increase statically induced EMF

Nullify statically induced EMF

Smooth current direction reversal

Maintain constant voltage

Question 19 of 56

Question 20 of 56

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

EMF decreases

No change in EMF

EMF increases

EMF becomes zero

Question 20 of 56

Question 21 of 56

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

BLV sinθ volts

BLV volts

BL sinθ volts

BLV cosθ volts

Question 21 of 56

Question 22 of 56

22. 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.

357 V

428 V

243 V

178 V

Question 22 of 56

Question 23 of 56

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

Soft iron

Aluminium

Cast iron

Rolled steel

Question 23 of 56

Question 24 of 56

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

Increased brush contact resistance

Additional interpoles

Resistance wires in windings

Compensating winding

Question 24 of 56

Question 25 of 56

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

Shift in MNA and GNA positions

Excessive brush spring tension

Short circuit in armature winding

Short circuit in field winding

Question 25 of 56

Question 26 of 56

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

640 V

480 V

160 V

320 V

Question 26 of 56

Question 27 of 56

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

Increase field strength

Spread flux uniformly in the air gap

Reduce air gap

Minimize magnetic losses

Question 27 of 56

Question 28 of 56

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

Low current, high voltage

High current, low voltage

Low current, low voltage

High current, high voltage

Question 28 of 56

Question 29 of 56

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

Reduce friction loss

Reduce hysteresis loss

Reduce copper loss

Reduce eddy current loss

Question 29 of 56

Question 30 of 56

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

Fleming's right hand rule

Cork screw rule

Fleming's left hand rule

Right hand palm rule

Question 30 of 56

Question 31 of 56

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

Reduce magnetizing current

Increase magnetic path reluctance

Increase air gap flux

Magnetize poles to produce flux

Question 31 of 56

Question 32 of 56

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

Enable air circulation

Lubrication

Fix the keyway

Easy shaft removal

Question 32 of 56

Question 33 of 56

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

Cumulative short shunt compound

Cumulative long shunt compound

Differential short shunt compound

Differential long shunt compound

Question 33 of 56

Question 34 of 56

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

Series generator

Compound generator

Separately excited generator

Shunt generator

Question 34 of 56

Question 35 of 56

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

Fleming’s left hand rule

Cork screw rule

Faraday’s laws of electromagnetic induction

Fleming’s right hand rule

Question 35 of 56

Question 36 of 56

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

Shunt generator

Differential compound generator

Cumulative compound generator

Series generator

Question 36 of 56

Question 37 of 56

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

Resistance between brush and commutator

Resistance between brush and armature conductors

Resistance between brush and commutator riser

Resistance between the opposite brushes

Question 37 of 56

Question 38 of 56

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

Mechanical energy

Chemical energy

Heat energy

Kinetic energy

Question 38 of 56

Question 39 of 56

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

To maintain constant output voltage

To reduce the field current

To reduce armature current

To build up the voltage

Question 39 of 56

Question 40 of 56

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

Maintain constant voltage

Collect current unidirectionally

Increase terminal voltage beyond rated

Reduce voltage drop at brushes

Question 40 of 56

Question 41 of 56

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

Armature core

Commutator segment

Commutator riser

Brush

Question 41 of 56

Question 42 of 56

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

Run armature with less weight

Reduce armature voltage drop

Reduce temperature of armature

Reduce armature current

Question 42 of 56

Question 43 of 56

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

Blowing hot air during maintenance

Regular commutator cleaning

Frequent brush replacement

Periodic machine heating

Question 43 of 56

Question 44 of 56

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

Yoke (or frame)

Pole shoes

Stator

Pole core

Question 44 of 56

Question 45 of 56

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

Separately excited generator

Compound generator

Series generator

Shunt generator

Question 45 of 56

Question 46 of 56

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

Pole shoe

Pole tip

Pole coil

Pole core

Question 46 of 56

Question 47 of 56

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

Reduce windage loss

Reduce hysteresis loss

Reduce friction loss

Reduce eddy current loss

Question 47 of 56

Question 48 of 56

48. 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 48 of 56

Question 49 of 56

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

Increased output voltage

Zero output voltage

Decreased output voltage

Pulsating output voltage

Question 49 of 56

Question 50 of 56

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

Armature core lamination

Commutator segment

Pole shoe lamination

Side end plates

Question 50 of 56

Question 51 of 56

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

B

A

D

C

Question 51 of 56

Question 52 of 56

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

Reduced brush voltage drop

Armature reaction effect

Increased armature resistance

Increased shunt field inductance

Question 52 of 56

Question 53 of 56

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

Short shunt compound generator

Long shunt compound generator

Cumulative compound generator

Differential compound generator

Question 53 of 56

Question 54 of 56

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

Field coil resistance increases

Loss of residual magnetism

Armature resistance increases

Increased armature reaction

Question 54 of 56

Question 55 of 56

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

Cumulative compound generator

Differential compound generator

Series generator

Shunt generator

Question 55 of 56

Question 56 of 56

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

Cork screw rule

Fleming’s right hand rule

Right hand palm rule

Fleming’s left hand rule

Question 56 of 56