Alternator MCQ | Synchronous Generator MCQ

121. In an alternator, the armature reaction considered to be equivalent to a fictitious

  1. Reactance
  2. Resistance
  3. Impedance
  4. Admittance
Answer
Answer. a

122. The rating of a synchronous machine is usually governed by its

  1. Speed
  2. Temperature rise
  3. Weight
  4. None of these
Answer
Answer. b

123. The power factor of an alternator driven by constant prime mover input can be changed by changing its

  1. Speed
  2. Load
  3. Field excitation
  4. Phase sequence
Answer
Answer. c

124. Three-phase alternators are invariably connected in star so as to

  1. Reduce the size of stator conductors used
  2. Increase the terminal voltage
  3. Reduce magnetic losses
  4. All options are correct
Answer
Answer. b

125. In a synchronous alternator, which of the following coils will have emf closer to sine wave form?

  1. Concentrated winding in full pitch coils
  2. Concentrated winding in short pitch coils
  3. Distributed winding in full pitch coils
  4. Distributed winding in short pitch coils
Answer
Answer. d

126. High speed alternators usually have

  1. salient pole rotors
  2. cylindrical rotors
  3. both salient pole and cylindrical rotors
  4. None of these
Answer
Answer. b

127. The ratio of armature leakage reactance to synchronous reactance of large size modern alternator is about

  1. 0.05
  2. 0.2
  3. 0.6
  4. 0.8
Answer
Answer. b

128. The short-circuit characteristic of an alternator is

  1. always linear
  2. always non-linear
  3. sometimes linear and sometimes non-linear
  4. None of these
Answer
Answer. a

129. The generator of power station produces an electric pressure by

  1. conversion of heat
  2. magnetic induction
  3. conversion of light
  4. mechanical pressure
Answer
Answer. d

130. The rated voltage of alternators used in power stations is usually

  1. 11 kV
  2. 66 kV
  3. 132 kV
  4. 400 kV
Answer
Answer. a
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