Quiz On Circuit Breaker

15 Questions | Total Attempts: 60

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Quiz On Circuit Breaker

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Questions and Answers
  • 1. 
    The medium employed for extinction of arc in air circuit breaker is
    • A. 

      (A) SF6

    • B. 

      (B) Oil

    • C. 

      (C) Air

    • D. 

      (D) Water.

  • 2. 
    Which of the following circuit breakers is preferred for EHT application
    • A. 

      (A) Air blast circuit breakers

    • B. 

      (B) Minimum oil circuit breakers

    • C. 

      (C) Bulk oil circuit breakers

    • D. 

      (D) SF6 oil circuit breakers.

  • 3. 
    For high voltage, ac circuit breakers, the rated short circuit current is passed for
    • A. 

      (A) 0.01 sec

    • B. 

      (B) 0.1 sec

    • C. 

      (C) 3 seconds

    • D. 

      (D) 30 seconds.

  • 4. 
    Interrupting medium in a contactor may be
    • A. 

      (A) air

    • B. 

      (B) oil

    • C. 

      (C) SF6 gas

    • D. 

      (D) any of the above.

  • 5. 
     In air blast circuit breakers, the pressure of air is of the order of
    • A. 

      (A) 100 mm Hg

    • B. 

      (B) 1 kg/cm2

    • C. 

      (C) 20 to 30 kg/cm2

    • D. 

      (D) 200 to 300 kg/cm2 

  • 6. 
     SF6 gas is
    • A. 

      (A) sulphur fluoride

    • B. 

      (B) sulphur difluoride

    • C. 

      (C) sulphur hexafluorine

    • D. 

      (D) sulphur hexafluoride.

  • 7. 
    SFgas
    • A. 

      (A) is lighter than hydrogen

    • B. 

      (B) is lighter than air

    • C. 

      (C) has density 2-times as compared to that of air

    • D. 

      (D) has density 5 limes as compared to that of air.

  • 8. 
    The pressure of SF6 gas in circuit breakers is of the order of
    • A. 

      (A) 100 mm Hg

    • B. 

      (B) 1 kg/cm2

    • C. 

      (C) 3 to 5 kg/cm2

    • D. 

      (D) 30 to 50 kg/cm2.

  • 9. 
     While selecting a gas for circuit breaker, the property of gas that should be considered is
    • A. 

      (A) high dielectric strength

    • B. 

      (B) non-inflammability

    • C. 

      (C) non-toxicity

    • D. 

      (D) all of the above.

  • 10. 
     A sudden short-circuit in an ac system causes a rise in __________ in the short-circuited phase.
  • 11. 
     The voltage appearing across the circuit breaker pole after final current zero is called __________ voltage.
  • 12. 
    The voltage across the circuit breaker pole after final current zero is recovery voltage.
    • A. 

      True

    • B. 

      False

  • 13. 
    Air circuit breakers are used for voltages above 12 kV.
    • A. 

      True

    • B. 

      False

  • 14. 
    Arcing contacts of circuit-breakers are generally made of copper tungsten alloy.
    • A. 

      True

    • B. 

      False

  • 15. 
    The insulation requirements of switchgear are determined by __________ voltage.
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