Alternator MCQ | Synchronous Generator MCQ

51. Synchronous impedance method of finding voltage regulation of an alternator is called pessimistic method because?

  1. It gives regulation value higher than its actual found by direct loading
  2. armature reaction is wholly magnetising
  3. it is simplest to perform and compute
  4. it gives regulation value lower than its actual found by direct loading
Answer
Answer. a

52. An alternator is supplying a load of 300 kW at a power factor of 0.6 lagging. If the power factor is raised to unity, how many more kW can alternator supply?

  1. 300 kW
  2. 100 kW
  3. 150 kW
  4. 200 kW
Answer
Answer. d

53. The per phase D.C. armature resistance of an alternator is 0.5 Ω. The effective A.C. armature resistance would be about?

  1. 0.25 ohm
  2. 0.5 ohm
  3. 1 ohm
  4. 0.75 ohm
Answer
Answer. d

54. Two alternators A and B are sharing the inductive load equally. What will happen when the excitation of A is increased?

  1. Current delivered by A will increase and of B will decrease
  2. Current of A will decrease and of B will increase
  3. Both will continue to share the load equally
  4. None of the above
Answer
Answer. a

55. Zero power factor method for an alternator is generally used to determine

  1. efficiency of alternator
  2. synchronous impedance of alternator
  3. voltage regulation of alternator
  4. All of the above
Answer
Answer. c

56. For cooling of large size generators hydrogen is used because

  1. it offers reduced fire risk
  2. it is light in weight
  3. it is of high thermal conductivity
  4. All the above
Answer
Answer. d

57. A salient pole synchronous generator connected to an infinite bus power will deliver maximum power at a power angle of

  1. δ = 0°
  2. δ = 90°
  3. δ = 30°
  4. δ = 45°
Answer
Answer. b

58. The angle between induced emf and terminal voltage on no-load for a single phase alternator is

  1. 180°
  2. 90°
  3. 0°
  4. 270°
Answer
Answer. c

59. The field winding of an alternator requires

  1. DC supply
  2. AC supply
  3. Pulsating DC
  4. Any of the above
Answer
Answer. a

60. Voltage regulation of an alternator may be negative where

  1. the load power factor is lagging
  2. the load power factor is leading
  3. it is loaded beyond its full load capacity
  4. the machine is run at very low loads
Answer
Answer. b
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