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EEE :: Transformers

  1. The secondary winding of which of the following transformers is always kept closed?

  2. A.

     Step-up transformer

    B.

     Step-down transformer

    C.

     Potential transformer

    D.

     Current transformer


  3. If a transformer is switched on to a voltage more than the rated voltage

  4. A.

     its power factor will deteriorate

    B.

     its power factor will increase

    C.

     its power factor will remain unaffected

    D.

     its power factor will be zero


  5. The transformer oil should have _____ volatility and _____ viscosity.

  6. A.

     low,low

    B.

     high,high

    C.

     low,high

    D.

     high,low


  7. The degree of mechanical vibrations produced by the laminations of a transformer depends on

  8. A.

     tightness of clamping

    B.

     gauge of laminations

    C.

     size of laminations

    D.

     all of the above


  9. The thickness of laminations used in a transformer is usually

  10. A.

     0.4 mm to 0.5 mm

    B.

     4 mm to 5 mm

    C.

     14 mm to 15 mm

    D.

     25 mm to 40 mm


  11. The core used in high frequency transformer is usually

  12. A.

     copper core

    B.

     cost iron core

    C.

     air core

    D.

     mild steel core


  13. A transformer transforms

  14. A.

     voltage

    B.

     current

    C.

     power

    D.

     frequency


  15. In a transformer the resistance between its primary and secondary is

  16. A.

     zero

    B.

     1 ohm

    C.

     1000 ohms

    D.

     infinite


  17. A transformer can have regulation closer to zero

  18. A.

     on full-load

    B.

     on overload

    C.

     on leading power factor

    D.

     on zero power factor


  19. Power transformers are designed to have maximum efficiency at

  20. A.

     nearly full load

    B.

     70% full load

    C.

     50% full load

    D.

     no load