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EEE :: Switchgear Protections

  1. Magnetic circuit breaker has ______ trip action.

  2. A.

     delayed

    B.

     instantaneous

    C.

     both of the above

    D.

     none of the above


  3. In a circuit breaker the basic problem is to

  4. A.

     maintain the arc

    B.

     extinguish the arc

    C.

     transmit large power

    D.

     emit the ionizing electrons


  5. The arcing contacts in a circuit breaker are made of

  6. A.

     copper tungsten alloy

    B.

     porcelain

    C.

     electrolytic copper

    D.

     aluminium alloy


  7. Air blast circuit breaker is used for

  8. A.

     over currents

    B.

     short duty

    C.

     intermittant duty

    D.

     repeated duty


  9. The steady state stability of the power system can be increased by

  10. A.

     Connecting lines in parallel

    B.

     Connecting lines in series

    C.

     Using machines of high impedance

    D.

     Reducing the excitation of machines


  11. The inductive interference between power and communication line can be minimized by

  12. A.

     transposition of the power line

    B.

     transposition of the communication line

    C.

     both (A) and (B)

    D.

     increasing the distance between the conductors


  13. A thermal protection switch can protect against

  14. A.

     short-circuit

    B.

     temperature

    C.

     overload

    D.

     over voltage


  15. Thermal circuit breaker has

  16. A.

     delayed trip action

    B.

     instantaneous trip action

    C.

     both of the above

    D.

     none of the above


  17. The time of closing the cycle, in modern circuit breakers is

  18. A.

     0.003 sec

    B.

     0.001 sec

    C.

     0.01 sec

    D.

     0.10 sec

    E.

     none of the above


  19. Transmission line has reflection coefficient as one.

  20. A.

     Open circuit

    B.

     Short-circuit

    C.

     Long

    D.

     None of the above