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EEE :: Switchgear Protections

  1. An isolator is installed

  2. A.

     to operate the relay of circuit breaker

    B.

     as a substitute for circuit breaker

    C.

     always independent of the position of circuit breaker

    D.

     generally on both sides of a circuit breaker


  3. Circuit breakers usually operate under

  4. A.

     transient state of short-circuit current

    B.

     sub-transient state of short-circuit current

    C.

     steady state of short-circuit current

    D.

     after D. C. component has ceased


  5. Overheating of relay contacts or contact born out is due to

  6. A.

     slow making and breaking of load circuit contacts

    B.

     foreign matter on the contact surface

    C.

     too low contact pressure

    D.

     all of the above


  7. To reduce short circuit fault currents are used.

  8. A.

     reactors

    B.

     resistors

    C.

     capacitors

    D.

     none of the above


  9. H.R.C. fuses provide best protection against

  10. A.

     overload

    B.

     reverse current

    C.

     open-circuits

    D.

     short-circuits


  11. D.C. shunt relays are made of

  12. A.

     few turns of thin wire

    B.

     few turns of thick wire

    C.

     many turns of thin wire

    D.

     many turns of thick wire


  13. ________ relay is preferred for phase fault on short transmission line.

  14. A.

     Induction type

    B.

     Reactance

    C.

     Impedance

    D.

     None of the above


  15. For the protection of power station buildings against direct strokes the requirements are

  16. A.

     interception

    B.

     interception and conduction

    C.

     interception, conduction and dissipation

    D.

     interception, conduction, dissipation and reflection

    E.

     none of the above


  17. The main function of a fuse is to

  18. A.

     protect the line

    B.

     open the circuit

    C.

     protect the appliance

    D.

     prevent excessive currents

    E.

     none of the above


  19. The information to the circuit breaker under fault conditions is provided by

  20. A.

     relay

    B.

     rewirable fuse

    C.

     H.R.'only

    D.

     all of the above