Hi Learners, in this article we have listed 60+ important MCQs on DC Generator which will be useful for your competitive exams, interview, viva, and other exams. The questions and answers are all collected from different exams and interviews of previous years.
Also Learn: 60+ Important MCQs on Transmission and Distribution
These listed MCQs are more than enough for your conceptual clarity and preparation about the DC Generator.
1. In dc generators, inter-pole field coils are connected on
A) in parallel with the load
B) in series with the load
C) in parallel with the armature winding
D) in series with the armature winding
Answer: D
2. Interpoles are usually wound with
A) interpoles do not need winding
B) insulation material
C) heavy gauge copper wire
D) very fine gauge copper wire
Answer: C
3. Total losses in a properly designed 1 kW dc generator may be of the order
A) 500 W
B) 250 W
C) 50 W
D) 5 W
Answer: C
4. If the no-load voltage of a certain generator is 220 V and the rated load voltage is 200 V, then the voltage regulation is
A) 10 %
B) 9%
C) 1%
D) 20 V
Answer: A
5. In a lap winding for a 4 pole machine, the number of parallel paths will be
A) 15
B) 8
C) 4
D) 2
Answer: C
6. Which of the following is not the function of the interpoles in dc generators?
A) Make commutation sparkles
B) Cool armature by ventilating air
C) Neutralization of reactance voltage
D) Neutralize cross magnetizing effects of an armature reaction
Answer: B
7. In dc generators the charge in voltage when the load is reduced from rated value to zero, expressed as a percentage of the rated load voltage, is known as
A) regulation
B) armature reactance
C) external efficiency
D) loss factor
Answer: A
8. If 0mbe the mechanical degrees, 0ebe the electrical degree and P be the number of poles on a dc generator, then which of the following relations is valid?
A) 0m= 20eP
B) 0e= 20mP
C) 0m = 20e/P
D) 0e = 20m/P
Answer: C
9. The direction of rotation of a shunt generator can be reversed by interchanging
A) the polarity of armature and field winding
B) the polarity of the field winding
C) the supply terminals
D) none of the above
Answer: B
10. In lap winding, the number of brushes is equal to
A) 4
B) 2
C) number of poles
D) 2 x number of poles
Answer: C
11. A 2-pole generator with wave would armature has 51 slots each having 24 conductors. The flux per pole is 0.01 Wb. The speed at which the generator should be run to induce the voltage of 220 should be
A) 1440 rpm
B) 1078 rpm
C) 750 rpm
D) 539 rpm
Answer: B
12. A 4-pole dynamo with wave would armature has 51 slots containing 20 conductors. The voltage induced is 357 V and the speed is 8500 rpm. The flux per pole will be
A) 21 x 10-3
B) 14 x 10-3Wb.
C) 1.2 x 10-3 Wb.
D) 3.5 x 10-3 Wb
Answer: C
13. For parallel operation, the generators normally preferred are
A) Series and shunt generators
B) Compound generators
C) Shunt generators
D) Series generators
Answer: C
14. The rotor of dc machines is usually supported in
A) ball or roller bearings
B) bush bearing
C) magnetic bearings
D) Plummer blocks
Answer: A
15. Each commutator segment is connected to the armature conductor by means of
A) resistance wire
B) copper lug
C) dielectric
D) insulator
Answer: B
16. The residual magnetism of a dc shunt generator can be regained by
A) reversing the direction of the generator
B) earthing the shunt field
C) running a generator on no load for sometime
D) connecting the shunt field to a battery
Answer: D
17. Which winding on dc generators is preferred for generating large currents?
A) Progressive wave winding
B) Lap winding
C) Reprogressive wave winding
D) None of the above
Answer: B
18. A two-layer lap would 4 pole generators with 16 coils will have a pole pitch of
A) 4
B) 8
C) 16
D) 32
Answer: B
19. Load saturation characteristic of a dc generator gives relations between
A) V and If
B) E and If
C) V and Ia
D) E and Ia
Answer: A
20. As a result of armature reaction, the total mutual air gap flux in a dc generator is approximately
A) 60 %
B) 50 %
C) 25 %
D) 5 %
Answer: D
21. The effect of iron losses on dc machines is
A) Loss of efficiency
B) Excessive heating of the core
C) (A) and (B) above
D) None of the above
Answer: C
22. Hysteresis loss in dc machine depends on
A) Frequency of magnetic reversals
B) Maximum value of flux density
C) Volume and grade of iron
D) All of the above
Answer: D
23. If a is the degree of multiplicity and P is the number of poles, the number of parallel paths in a wave winding will be
A) 2 a p
B) a p
C) 2 a
D) 2
Answer: D
24. Two dc generators have similar characteristics. The essential condition for stable parallel operation of these two generators is that they should have
A) Same drooping voltage characteristic
B) Same speeds at on load as well as full loads
C) Same percentage regulation
D) Same kilowatt output ratings
Answer: A
25. For wave winding, the average pitch must be
A) fractional
B) odd or even
C) even
D) odd
Answer: B
26. The armature voltage control is considered suitable, in case the dc machine is driven at
A) Constant current
B) Constant load
C) Constant speed
D) Constant torque
Answer: D
27. For a fixed number of poles and armature conductors, which winding will be higher emf?
A) Wave winding
B) Lap winding
C) Any of the above
Answer: A
28. When B is the maximum flux density, then eddy current loss varies a
A) B2
B) B2
C) B1.6
D) B
Answer: B
29. Equalizer rights are required in a lap winding dc machine
A) To filter out harmonics
B) To prevent the flow of circulating current through the brushes
C) To improve commutation
D) To decrease armature reaction
Answer: B
30. When a dc generator is operating at a constant speed, variable load, which loss is likely to vary significantly
A) Copper loss
B) Eddy’s current loss
C) Bearing friction loss
D) Windage loss
Answer: A
31. In a dc generator, the polarity of the Interpole is
A) Same as the polarity of the main pole that follows in the direction of rotation
B) Same as the polarity of the main pole that precedes in the direction of rotation
C) Always S
D) Always N
Answer: B
32. The commutator in a dc machine can converts
A) dc to ac
B) ac to dc
C) both (A) and (B)
D) none of these
Answer: C
33. Hysteresis loss in a dc shunt generator
A) depends only on the lamination thickness
B) varies as 1.6 power flux density
C) varies as the inverse of flux density
D) can be minimized by laminating the armature
Answer: B
34. In a dc generator if field winding attains the critical resistance
A) the voltage generated will be zero
B) field winding will burn
C) machine will generate maximum power
D) machine will generate a maximum voltage
Answer: A
35. If A be the commercial efficiency, B be the electrical efficiency and C be the mechanical efficiency of a dc generator then which of the following relations is valid?
A) A = B x C
B) C = A + B
C) B = A x C
D) C = A x B
Answer: A
36. Among the series and shunt generators, which generator has the better regulation
A) Shunt generator
B) Series generator
C) Both have identical regulation
Answer: A
37. The armature reaction of an unsaturated dc machine is
A) Cross-magnetizing
B) Demagnetizing
C) Magnetizing
D) Non-magnetizing
Answer: A
38. In a generator, the winding loss is proportional to
A) flux density
B) square of armature speed
C) square of the supply current
D) supply voltage
Answer: B
39. When the field resistance of a dc shunt generator is increased beyond its critical value, the generator
A) power output may exceed the rated power
B) winding may burn out
C) will start ‘hunting’
D) will not build-up
Answer: D
40. Which of the following is closest to the armature circuit resistance of a dc generator?
A) 20000 ohms
B) 1000 ohms
C) 200 ohms
D) 1 ohm
Answer: D
41. A dc shunt generator has full load voltage regulation of 5% at rated speed of 400 rpm. The generator is new driven at 500 rpm. Its voltage regulation now will be
A) more than 5 percent
B) 5 percent
C) less than 5 percent
D) 4 percent
Answer: A
42. The yoke of a small dc machine is made of
A) stainless steel
B) cast iron
C) aluminum
D) copper
Answer: B
43. The pole shoe of a dc machine is laminated for the purpose of
A) decreasing hysteresis loss
B) decreasing eddy current loss
C) both (A) abs (B)
D) none of them
Answer: B
44. Two generators having series excitation are connected in parallel. If equalizer bar is not used
A) generator with lower shunt resistance will share mare load
B) both generators may start hunting
C) one of the generators may get reversed
D) one of the generators may stop
Answer: C
45. The core of the armature is made of silicon steel due to
A) more mechanical strength
B) high permeability
C) low permeability
D) both (B) and (C)
Answer: D
46. The magnetic field which initially induces armature current in a self-excited generated is caused by
A) rotation of the armature
B) an external dc source
C) residual magnetism
D) permanent magnet
Answer: C
47. Equalizer connections are required when paralleling two
A) compound generators
B) series generators
C) shunt generators
D) bipolar generators
Answer: A
48. For a 6 pole wave would dc generator the number of brushes will be
A) 2
B) 4
C) 6
D) 12
Answer: A
49. The drop-in speed of a dc generator due to increases in load can be compensated by
A) increasing armature resistance
B) cooling the armature
C) reducing load voltage
D) increasing input to the prime mover
Answer: D
50. The terminal voltage of a dc shunt generator on loading
A) remain constant
B) decreases sharply
C) decreases slightly
D) increases slightly
Answer: C
51. Series field winding of dc machine consists of
A) many turns of thin wire
B) many turns of thick wire
C) a few turns of thin wire
D) few turns of thick wire
Answer: D
52. When P is the number of poles in a lap wound dc generator, the number of brushes will be
A) P
B) 2P
C) (2P + 2)
D) P/2
Answer: A
53. The shunt field winding of dc machine consists of
A) many turns of thin wire
B) many turns of thick wire
C) few turns of thin wire
D) few turns of thick wire
Answer: A
54. The principle of dc generator is based on
A) mutually induced emf
B) dynamically induced emf
C) self-induced emf
D) all of them
Answer: B
55. The component of a dc generator which plays a vital role in providing direct current is
A) brushes
B) commutator
C) equalizer ring
D) dummy coils
Answer: B
56. A 4-pole dc generator is running at 1500 rpm. The frequency of the current in the armature is
A) 60 Hz
B) 50 Hz
C) 25 Hz
D) 100 Hz
Answer: B
57. A Dummy coil in a dc generator is provided to reduce
A) tendency for reversal
B) armature reaction
C) hysteresis losses
D) mechanical unbalance
Answer: D
58. Electromagnetic torque and speed are in opposite directions in case of
A) shunt generators
B) shunt motors
C) series motors
D) all of the above
Answer: A
59. The generated emf and current are in the same direction in case of
A) series motors
B) shunt motors
C) dc generators
D) none of the above
Answer: C
60. An 8-pole dc machine has wave winding. The winding is removed and then rewound as lap winding. The induced emf will
A) increase
B) reduce
C) remain unchanged
D) none of these
Answer: B
These are our top 3 MCQ questions that might help you in various exams!!
1. 26 Most Asked Electrical Engineering Interview Questions and Answers [With PDF]
2. 60+ Important MCQs on Transmission and Distribution
3. 150+ V. Important Synchronous Motor MCQ Questions and Answers
Share this article with your friends who are also Electrical and electronics engineers. Lastly, if you have any questions to ask feel free to comment down below, we will reply to you back right away.
