17th
Apr
Switchgear & Protection MCQ

Switchgear & Protection MCQ

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  • 17th Apr, 2021
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Switchgear & Protection MCQ Test

Following are mostly asked Switchgear & protection MCQ test that are designed for professionals like you to crack you interviews. You can take this Switchgear & protection online test before appearing to you real interview. This Switchgear & protection quiz there are around 30+ multiple choice questions on Switchgear & protection with four options.

1) In a circuit breaker the contact space is ionised by what?

  • A. Thermal ionisation of gas
  • B. Field emission from the contact surface
  • C. Thermal emission from the contact surface
  • D. None of the above

2) SF6 is which type of gas?

  • A. Electro negative
  • B. Electro positive
  • C. Both (a) and (b)
  • D. None of the above

3) Which of the following circuit breakers is used for the railway electrification?

  • A. SF6 circuit breaker
  • B. Bulk oil circuit breaker
  • C. Air blast circuit breaker
  • D. Minimum oil circuit breaker

4) Circuit breakers usually operate under ............

  • A. Steady short circuit current
  • B. Transient state of short circuit current
  • C. Sub transient state of short circuit current
  • D. None of the above

5) What is the actuating quantity for the relays?

  • A. Frequency
  • B. Magnitude
  • C. Phase angle
  • D. All of the Above

6) Which among these are the main characteristics of a fuse element?

  • A. High conductivity
  • B. Low melting point
  • C. Least deterioration due to oxidation
  • D. All of the Above

7) Why is an isolator installed?

  • A. It used on either sides of the circuit breaker
  • B. To isolate one portion of the circuit from another
  • C. As an substitute for the circuit breaker
  • D. Both A & B

8) What is the cut off current in the fuse?

  • A. Rms value actually reached.
  • B. Average value actually reached.
  • C. Maximum value actually reached.
  • D. None of the above

9) Which circuit breaker is preferred to be installed in extra high voltage AC system?

  • A. SF6 circuit breaker
  • B. Air blast circuit breaker
  • C. Bulk oil type circuit breaker
  • D. Vacuum circuit breaker

10) What is switchgear?

  • A. It corrects the faults only.
  • B. It detects the faults only.
  • C. An apparatus used for switching, controlling and protecting the electrical circuits and equipments.
  • D. All of the Above

11) The most efficient torque producing actuating structure for the induction type relays is ..............

  • A. Induction cup structure
  • B. Shaded pole structure
  • C. Watt hour meter structure
  • D. Single induction loop structure

12) Plug setting of a electromagnetic relay can be altered by varying ...........

  • A. Adjustable back stop
  • B. Air gap of magnetic path
  • C. Number of ampere turns
  • D. None of the above

13) protective relays can be designed to respond to ...........

  • A. Voltage and current
  • B. Light intensity, impedance
  • C. Temperature, resistance, reactance
  • D. All of the Above

14) What is the purpose of back up protection?

  • A. To leave no blind spot
  • B. To increase the reach
  • C. To increase the speed
  • D. To guard against failure of primary

15) What is the purpose of back up protection?

  • A. To leave no blind spot
  • B. To increase the reach
  • C. To increase the speed
  • D. To guard against failure of primary

16) What is the major cause of the failure of the circuit breaker?

  • A. Trip circuit open
  • B. Spring defective
  • C. Trip latch defective
  • D. All of the Above

17) why are the isolators used ...........

  • A. Break abnormal current
  • B. Making under fault conditions
  • C. Breaking the circuit under no load condition
  • D. None of the above

18) What is the making to breaking current ratio for an extra high voltage circuit breaker?

  • A. Equal to 1
  • B. Less than 1
  • C. More than 1
  • D. A negative value

19) Which among these circuit breakers produce the least arc energy?

  • A. Air blast
  • B. Air break
  • C. Plain oil
  • D. Minimum oil

20) A thermal protection switch provides protection against what?

  • A. Overload
  • B. Short circuit
  • C. Temperature
  • D. Over voltage

21) What is the advantage of using oil as the arc quenching medium?

  • A. Acts as an insulator.
  • B. High dielectric strength.
  • C. Good cooling properties.
  • D. All of the Above

22) When does the arc interruption in oil circuit breaker take place?

  • A. Contacts apart.
  • B. Voltages becomes zero
  • C. Current goes through zero
  • D. All of the Above

23) The main function of a fuse is to ..............

  • A. Protect the line
  • B. Open the circuit
  • C. Prevent excessive currents
  • D. All of the Above

24) On which of the following routine tests are conducted?

  • A. Oil circuit breakers
  • B. Air blast circuit breakers
  • C. Minimum oil circuit breakers All of the above
  • D. All of the Above

25) The arcing contacts in a circuit breaker are made of ..............

  • A. Porcelain
  • B. Aluminum alloy
  • C. Electrolytic copper
  • D. Copper tungsten alloy

26) Which of the following medium is employed for the extinction of arc in air circuit breaker?

  • A. Oil
  • B. Air
  • C. Water
  • D. None of the above

27) With which of the following, a circuit breaker must be equipped for remote operation?

  • A. Shunt trip
  • B. Time-delay trip
  • C. Inverse time trip
  • D. None of the above

28) A protective device, which reduces the steepness of wavefront of a surge by absorbing surge energy is called ..............

  • A. Earthing screen
  • B. Surge absorber
  • C. Surge Diverters
  • D. Switching surges

29) A thermal protection switch can protect against ..............

  • A. Overload
  • B. Overvoltage
  • C. Temperature
  • D. Short-circuit

30) Arc in a circuit behaves as .............

  • A. A capacitive reactance
  • B. An inductive reactance
  • C. A resistance decreasing with voltage rise across the arc
  • D. A resistance increasing with voltage rise across the arc

31) Relays can be designed to respond to changes in ...........

  • A. Temperature
  • B. Voltage and current
  • C. Resistance, reactance or impedance
  • D. All of the Above

32) Thermal overload relays are used to protect the motor against over current due to ...........

  • A. Grounds
  • B. Heavy loads
  • C. Short-circuits
  • D. All of the Above

33) The function of the circuit breaker is ............

  • A. On and off the circuit
  • B. To save human life
  • C. To safeguard the circuit
  • D. None of the above

34) Circuit breakers usually operate under ..........

  • A. After D.C. component has ceased
  • B. Transient state of short-circuit current
  • C. The steady state of short-circuit current
  • D. Sub-transient state of short-circuit current

35) The burden of a protective relay is the power .........

  • A. Absorbed by the circuit of relay
  • B. Developed by the relay circuit
  • C. Required to operate the circuit breaker
  • D. None of the above

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