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EEE :: Circuit Breakers

  1. In a circuit breaker the active recovery voltage depends upon
  2. A.
    power factor
    B.
    armature reaction
    C.
    circuit conditions
    D.
    all of the above

  3. The transient voltage that appears across the contacts at the instant of arc extinction is called
  4. A.
    recovery voltage
    B.
    re striking voltage
    C.
    supply voltage
    D.
    peak voltage

  5. The normal frequency rms voltage that appears across the breaker poles after final arc extinction has occurred, is
  6. A.
    recovery voltage
    B.
    re striking voltage
    C.
    supply voltage
    D.
    peak voltage

  7. If a circuit breaker does not operate on electrical compound, the probable reason could be
  8. A.
    spring defective
    B.
    trip circuit open
    C.
    trip latch defective
    D.
    any of the above

  9. In a circuit breaker if the insulation resistance between phase terminal and earthed frame is less than the specified limit, the probable cause could be
  10. A.
    moisture
    B.
    dirty insulation surface
    C.
    carbon or copper particles sticking to the internal surface
    D.
    any of the above

  11. There is definite objection to use of which of the following medium for extinguishing the arc in case of a circuit breaker ?
  12. A.
    Air
    B.
    SF6 gas
    C.
    Vacuum
    D.
    Water

  13. The insulation resistance of high voltage circuit breaker is
  14. A.
    1k Ohm
    B.
    10 k Ohm
    C.
    20 Mega ohms
    D.
    2000 Mega ohm

  15. The contact resistance of a circuit breaker is. of the order of
  16. A.
    20 micro ohms ± 10
    B.
    20 milli ohms ± 10
    C.
    20 ohms ± 10
    D.
    200 ohms ± 10

  17. Which of the following circuit breakers does not use pneumatic operating mechanism
  18. A.
    Air blast circuit breaker
    B.
    SF6 blast circuit breaker
    C.
    Air break circuit breaker
    D.
    Bulk-oil circuit breaker

  19. Fusing factor for a HRC fuse is
  20. A.
    Minimum fusing current / Current rating
    B.
    Minimum fusing current / Minimum rupturing time
    C.
    Maximum fusing current / Minimum fusing current
    D.
    Minimum fusing current / Prospective current of circuit