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EEE :: Switchgear Protections

  1. The under voltage relay can be used for

  2. A.

     generators

    B.

     busbars

    C.

     transformers

    D.

     motors

    E.

     all of the above


  3. In order that current should flow without causing excessive heating or voltage drop, the relay contacts should

  4. A.

     Have low contact resistance

    B.

     Be clean and smooth

    C.

     Be of sufficient size and proper shape

    D.

     Have all above properties


  5. On which of the following effects of electric current a fuse operates?

  6. A.

     Photoelectric effect

    B.

     Electrostatic effect

    C.

     Heating effect

    D.

     Magnetic effect


  7. Ionization in circuit breaker is facilitated by

  8. A.

     high temperature

    B.

     increase of mean free path

    C.

     increasing field strength

    D.

     all of the above


  9. Arc in a circuit breaker is interrupted at

  10. A.

     zero current

    B.

     maximum current

    C.

     minimum voltage

    D.

     maximum voltage


  11. Fault diverters are basically

  12. A.

     fuses

    B.

     relays

    C.

     fast switches

    D.

     circuit breakers


  13. Relays can be designed to respond to changes in

  14. A.

     resistance, reactance or impedance

    B.

     voltage and current

    C.

     light intensity

    D.

     temperature

    E.

     all above


  15. On which of the following routine tests are conducted ?

  16. A.

     Oil circuit breakers

    B.

     Air blast circuit breakers

    C.

     Minimum oil circuit breakers

    D.

     All of the above


  17. Relays are used for phase faults on long line.

  18. A.

     Impedance

    B.

     Reactance

    C.

     Either of the above

    D.

     None of the above


  19. By which of the following methods major portion of the heat generated in a H.R.C. fuse is dissipated ?

  20. A.

     Radiation

    B.

     Convection

    C.

     Conduction

    D.

     All of the above