Protective Relays - MCQs with answers

Protective Relays - MCQs with answers


Q1. What is the purpose of back up protection?

a. To increase the speed
b. To increase the reach
c. To leave no blind spot
d. To guard against failure of primary

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ANSWER: d. To guard against failure of primary



Q2. What is the actuating quantity for the relays?

a. Magnitude
b. Frequency
c. Phase angle
d. All of these

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ANSWER: d. All of these



Q3. Protective relays can be designed to respond to ___________

a. Light intensity, impedance
b. Temperature, resistance, reactance
c. Voltage and current
d. All of these

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ANSWER: d. All of these



Q4. On what factor does the operating speed of the relay depend upon?

a. Rate of flux built up
b. Armature core air gap
c. Spring tension
d. All of these

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ANSWER: d. All of these




Refer to the diagram below to answer Question 5 to Question 8

V Curves For Synchronous Generator

Q5. In the above figure, the relay circuit is divided into three parts. What does the first part consist of?

a. Primary winding of a current CT which is connected in series with the line to be protected.
b. Secondary of the CT and the operating coil.
c. Tripping circuit.
d. All of these.

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ANSWER: a. Primary winding of a current CT which is connected in series with the line to be protected.



Q6. What does the third part consist of?

a. Primary winding of a current CT which is connected in series with the line to be protected.
b. Secondary of the CT and the operating coil.
c. Tripping circuit.
d. All of these.

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ANSWER: c. Tripping circuit.



Q7. Which component ensures the safety of the line from damage?

a. Relay
b. Circuit breaker
c. Bus bar
d. Current transformer

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ANSWER: a. Relay



Q8. The tripping circuit is__________

a. AC
b. DC
c. Either AC or DC
d. None of these

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ANSWER: c. Either AC or DC



Q9. Plug setting of a electromagnetic relay can be altered by varying

a. Number of ampere turns
b. Air gap of magnetic path
c. Adjustable back stop
d. None of these

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ANSWER: a. Number of ampere turns



Q10. The most efficient torque producing actuating structure for the induction type relays is

a. Shaded pole structure
b. Watt hour meter structure
c. Induction cup structure
d. Single induction loop structure

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ANSWER: c. Induction cup structure


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    Discussion

  • RE: Protective Relays - MCQs with answers -Neelam kulaste (01/30/21)
  • power system operation and protection
  • Protective Relays - MCQs with answers -Chrispin (06/30/15)
  • Q11. What do protective relays provide?

    a. Provide additional safety to the circuit breaker in its operation.
    b. Close the contacts when the actuating quantity attains a certain predetermined value.
    c. Limit the arcing current during the circuit breaker operation.
    d. Earth or ground any stray voltage.

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    ANSWER: b. Close the contacts when the actuating quantity attains a certain predetermined value.


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