Quiz  /  Phase Transformation 1 st MCQ Questions With Answers

  • 1. 
    For a delta-star three phase transformer, if the transformation ratio is ‘x:1’, then how much percent of output will be improved?

  • 73%
  • 57%
  • 173%
  • 157%

  • 2. 
    Operating transformers in parallel gives the advantage of ___________

  • reliable loading
  • increased capacity of power system
  • reducing the capacity of substation
  • all of the mentioned

  • 3. 
    Which of the following is a shortcoming for using parallel connected transformers?I. Reliable loadingII. Increased capacity of power systemIII. Reducing the capacity of substation

  • I, II, III
  • I, II
  • I, III
  • None of the mentioned

  • 4. 
    Two single phase transformers A and B are operating in parallel having same impedance. But the x/r ratio of them are not equal and xa > xb. Then?

  • A has poorer pf than B
  • B has poorer pf than B
  • lesser power factor angle
  • both operate at same power factor

  • 5. 
    Which if the conditions is must be fulfilled for satisfactory parallel operation of transformers?

  • Same voltage ratio
  • Leakage impedances should be inversely proportional to kVA of the transformer
  • Same pu impedance
  • Correct polarity

  • 6. 
    Identify the correct order for the voltage transformation for the three-phase transformers.

  • D-Y > D-D = Y-Y > Y-D
  • D-Y > D-D > Y-Y > Y-D
  • D-Y > D-D = Y-Y < Y-D
  • D-Y > D-D < Y-Y < Y-D

  • 7. 
    For a star-delta three phase transformer, if the transformation ratio is ‘x:1’, then how much percent of output will be?

  • 73%
  • 57%
  • 173%
  • 157%

  • 8. 
    Which of the following is the correct matching made for the harmonics and the associated harmonic component?A. Positive sequence components - 5th harmonic componentB. Negative sequence components - 7th harmonic componentC. Zero sequence components - 3rd harmonic component

  • A, B, C
  • C
  • A, B
  • B, C

  • 9. 
    Transformer operating in parallel will share a common load in the best possible manner if ____________

  • leakage impedances are proportional to their kVA rating
  • pu leakage impedances are equal
  • leakage impedances are equal
  • any of the mentioned

  • 10. 
    Two single phase transformers A and B are operating in parallel having same impedance. But the x/r ratio of them are not equal. Then total kVA output of the output will be ___________

  • less than sum of kVA of A and B
  • more than sum of kVA of A and B
  • equal to sum of kVA of A and B
  • any of the mentioned

  • 11. 
    A 2000/1000/500 three winding transformer is to be used as auto transformer with supply of 3000 V. Two loads of 1050 kVA at 3500V and other one at 180 kVA at 1000V. The total kVA supplied will be?

  • 1230 kVA
  • 1440 kVA
  • 1680 kVA
  • 1150 kVA

  • 12. 
    In three phase supply, the voltage phases are displaced by ________ and in two phase by ___________

  • 120°, 90°
  • 180°, 90°
  • 120, 120°
  • 120°, 180°
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