Alternator MCQ | Synchronous Generator MCQ

91. Harmonics in the power system are not generated by

  1. Unbalanced source and balanced load
  2. Balanced source and unbalanced load
  3. Balanced loading with a balanced source
  4. Non-linear switches
Answer
Answer. c

92. The statement”Generators are Coherent”, implies that

  1. All of them oscillate at the same frequency
  2. Each of them oscillates at different frequencies
  3. They rotate at the same frequency
  4. Each generator rotates at a different frequency
Answer
Answer. a

93. A synchronous generator has a higher power handling capacity when operating

  1. at lagging power factor
  2. at leading power factor
  3. at unity power factor
  4. independent of power factor
Answer
Answer. c

94. Which one of the following methods gives more accurate result for determination of voltage regulation of an alternator?

  1. m.m.f. method
  2. Synchronous impedance method
  3. American institution standard method
  4. Potier triangle method
Answer
Answer. d

95. The per unit parameter for a 500 MVA machine on its own base are

Inertia constant, M = 20 p.u.

Reactance, X = 2 p.u.

The per unit value of inertia constant and reactance on 100 MVA common base are respectively

  1. 4 and 0.4
  2. 100 and 10
  3. 4 and 10
  4. 100 and 0.4
Answer
Answer. d

96. The neutral of 10 MVA, 11 KV alternator is earthed through a resistance of 5 ohms. The earth fault relay is set to operate at 0.75 A. The CTs have the ratio of 1000 : 5. What percentage of the alternator winding is protected?

  1. 88%
  2. 85%
  3. 12%
  4. 15%
Answer
Answer. a

97. A 500 MW, 3-phase star connected synchron0us generator has a rated voltage of 21.5 kV at 0.85 pf. What will be the line current when operating at full load rated conditions?

  1. 13.43 kA
  2. 15.79 kA
  3. 27.36 kA
  4. 23.25 kA
Answer
Answer. b

98. An alternator is connected to an infinite bus. If its field current is decreased then its armature current will be

  1. Increases with zero pf laggıng
  2. Decreases with zero pf leading
  3. Increases with zero pf leading
  4. None of the other options
Answer
Answer. b

99. An alternator is feeding an infinite bus bar. Its prime mover is suddenly shutdown. The alternator will

  1. Continue to work as alternator but the direction of rotation will reverse.
  2. Come to stand still
  3. Continue to work as synchronous motor and direction of rotation will also be same
  4. Will work as an induction motor
Answer
Answer. c

100. A 60 Hz, 4 pole turbo generator rated 100 MVA, 13.8 kV has an inertia constant of 10 MJ/MVA. Find the stored energy in the rotor at synchronous speed.

  1. 10 MJ
  2. 100 J
  3. 1 kJ
  4. 1000 MJ
Answer
Answer. d
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