Electrical machines (Transformer)

1) In a transformer the coils of primary and secondary are placed concentrically to achieve
      A. reduced leakage flux between primary and secondary winding
      B. reduced copper losses in the winding
      C. reduced insulation cost of the windings
      D. reduced voltage per turn in the winding

 2) Iron loss in transformer can be determined by
      A. Short Circuit Test
      B. Open Circuit Test
      C. Both Short Circuit and Open Circuit Tests
      D. None of the above

3) No Load Losses in transformer can be minimized by using steel of
      A. high silicon content and very thin lamination
      B. only high silicon content
      C. only very thin lamination
      D. low silicon content and very thin lamination

4) Which of the following losses remain constant during normal operation of transformer?
      A. Copper loss
      B. Core loss
      C. Stray loss
      D. All losses in transformer vary with load

 5) Which of the following losses varies with load in transformer?
      A. Copper loss
      B. Hysteresis loss
      C. Eddy Current loss
      D. All losses in transformer vary with load.

6) The maximum efficiency of a transformer occurs when
      A. Iron loss > Copper loss
      B. Iron loss < Copper loss
      C. Iron loss = Copper loss
      D. Iron loss = zero


7) Which one of the following is not a condition of parallel operation of transformer?
      A. MVA Rating of transformers must be same
      B. Voltage ration of transformers must be same
      C. Percentage Impedance of transformers should be same
      D. Polarity of transformers must be identical

 8) If the supply frequency of a transformer increases the output voltage of the transformer will
      A. decrease.
      B. increase proportionately
      C. remain same
      D. increases very rapidly

 9) In a core type transformer
      A. HV winding is placed nearer to the core limb.
      B. LV winding is placed nearer to the core limb.
      C. Any of the LV or HV can be placed nearer to the core limb.
      D. HV and LV windings are placed in different core limbs.

10) The primary and secondary winding of a transformer are
      A. conductively linked.
      B. inductively linked.
      C. electrically linked.
      D. mechanically linked.

Answers:
1. a
2. b
3. a
4. b
5. a
6. c
7. a
8. b
9. b
10. b

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