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EEE :: Transformers

  1. A transformer can have zero voltage regulation at

  2. A.

     leading power factor

    B.

     lagging power factor

    C.

     unity power factor

    D.

     zero power factor


  3. The secondary of a current transformer is always short-circuited under operating conditions because it

  4. A.

     avoids core saturation and high voltage induction

    B.

     is safe to human beings

    C.

     protects the primary circuit

    D.

     none of the above


  5. The 'cogging' of an induction motor can be avoided by

  6. A.

     proper ventilation

    B.

     using DOL starter

    C.

     auto-transformer starter

    D.

     having number of rotor slots more or less than the number of stator slots (not equal)


  7. Which of the following is not a part of transformer installation?

  8. A.

     Conservator

    B.

     Breather

    C.

     Buchholz relay

    D.

     Exciter


  9. Which winding of the transformer has less cross-sectional area?

  10. A.

     Primary winding

    B.

     Secondary winding

    C.

     Low voltage winding

    D.

     High voltage winding


  11. The complete circle diagram of induetion motor can be drawn with the help of data found from

  12. A.

     noload test

    B.

     blocked rotor test

    C.

     stator resistance test

    D.

     all of the above


  13. A common method of cooling a power transformer is

  14. A.

     natural air cooling

    B.

     air blast cooling

    C.

     oil cooling

    D.

     any of the above


  15. An open-circuit test on a transformer is conducted primarily to measure

  16. A.

     insulation resistance

    B.

     copper loss

    C.

     core loss

    D.

     total loss


  17. In a transformer the energy is conveyed from primary to secondary

  18. A.

     through cooling coil

    B.

     through air

    C.

     by the flux

    D.

     none of the above


  19. The voltage transformation ratio of a transformer is equal to the ratio of

  20. A.

     primary turns to secondary turns

    B.

     secondary current to primary current

    C.

     secondary induced e.m.f. to primary induced e.m.f.

    D.

     secondary terminal voltage to primary applied voltage