Testing And Commissioning Of Electrical Equipment’S Set 5

Electrical Engineering

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This set of Testing and Commissioning of Electrical Equipment’s Multiple Choice Questions & Answers (MCQs) focuses on Testing And Commissioning Of Electrical Equipment’S Set 5

Q1 | What is the actuating quantity for the relays?
  • Magnitude
  • Frequency
  • Phase angle
  • All of these
Answer: All of these
Q2 | Which among these are the main characteristics of a fuse element?
  • Low melting point
  • High conductivity
  • Least deterioration due to oxidation
  • All of the above
Answer: All of the above
Q3 | What is the making capacity of the circuit breaker?
  • Less than the asymmetrical breaking capacity of the breaker
  • Greater than the asymmetrical breaking capacity of the breaker
  • Equal to the asymmetrical breaking capacity of the breaker
  • Equal to the symmetrical breaking capacity of the breaker
Answer: Greater than the asymmetrical breaking capacity of the breaker
Q4 | In a circuit breaker the contact space is ionised by what?
  • Field emission from the contact surface.
  • Thermal emission from the contact surface.
  • Thermal ionisation of gas.
  • All of above.
Answer: Thermal ionisation of gas.
Q5 | A three phase, 33 kV oil circuit breaker is rated 1200 A, 2000 MVA, 3s. What isits symmetrical breaking current?
  • 1200 A
  • 3600 A
  • 35 kA
  • 104.8 kA
Answer: 35 kA
Q6 | What should be the value of fusing factor?
  • Equal to zero
  • Equal to one
  • Less than one
  • More than one
Answer: Less than one
Q7 | What is the relation between the fusing current and the diameter of the wire?
  • I = k d3
  • I = k d3/2
  • I = k d2
  • I = k d2/3
Answer: I = k d3/2
Q8 | The making and breaking currents of a 3 phase ac circuit breakers in powersystems are respectively in ________form.
  • rms value, rms value
  • instantaneous value, rms value
  • rms value, instantaneous value
  • instantaneous value, instantaneous value
Answer: instantaneous value, instantaneous value
Q9 | Why is an isolator installed?
  • To isolate one portion of the circuit from another
  • As an substitute for the circuit breaker
  • It used on either sides of the circuit breaker
  • Both (a) and (c)
Answer: To isolate one portion of the circuit from another
Q10 | Assertion (A): In comparison to making capacity of a circuit breaker its breakingcapacity is normally higher. Reason (R): The breaking capacity of a CB is expressed as ?3 * VI * 10-6 MVA
  • Both A and R are true and R is the correct explanation of A
  • Both A and R are true and R is not the explanation of A
  • A is true but R is false
  • A is false but R is true.
Answer: A is false but R is true.
Q11 | What is the cut off current in the fuse?
  • Maximum value actually reache(D)
  • Rms value actually reache(D)
  • Average value actually reach
Answer: Maximum value actually reache(D)
Q12 | Which circuit breaker is preferred to be installed in extra high voltage ACsystem?
  • Bulk oil type circuit breaker
  • Air blast circuit breaker
  • SF6 circuit breaker
  • Vacuum circuit breaker
Answer: SF6 circuit breaker
Q13 | A three phase circuit breaker is rated 2000 MVA, 33 kV. What will be its makingcurrent?
  • 35 kA
  • 49 kA
  • 70 kA
  • 89 kA
Answer: 89 kA
Q14 | A fuse wire of circular cross section has a radius of 0.8mm. The wire blows off at a current of 9(A) What will be the radius of the wire that will blow off at a current of 1A?
  • 0.2 mm
  • 0.18 mm
  • 0.28 mm
  • 0.3 mm
Answer: 0.18 mm
Q15 | Which among these tests are performed to check the nation or internationalstandards?
  • Type test.
  • Production tests.
  • Site checks.
  • All of the above.
Answer: Type test.
Q16 | Refer to the following facts to answer the question A 50 Hz, 11 kV, 3 phase alternator with earthed neutral having a reactance of 3 ohms per phase and is connected to a bus bar through a circuit breaker, if the distributed capacitance upto CB between the phase and neutral is 0.01 ? F. What is the frequency of oscillations?
  • 10000 Hz
  • 12500 Hz
  • 12628 Hz
  • 13265 Hz
Answer: 12628 Hz
Q17 | What is switchgear?
  • An apparatus used for switching, controlling and protecting the electrical circuits and equipments.
  • It detects the faults only.
  • It corrects the faults only.
  • All of the above.
Answer: All of the above.
Q18 | What is / are the main disadvantage / s of using oil as the quenching medium in the circuit breakers?
  • Need periodical replacement.
  • Risk of formation of explosive mixture with air.
  • Possibility of causing fire hazards.
  • All of the above.
Answer: All of the above.
Q19 | Which of the following circuit breakers has the lowest operating voltage?
  • SF6 circuit breaker
  • Air break
  • Air blast
  • Minimum oil circuit breaker
Answer: Air break
Q20 | The most efficient torque producing actuating structure for the induction typerelays is
  • Shaded pole structure
  • Watt hour meter structure
  • Induction cup structure
  • Single induction loop structure
Answer: Induction cup structure
Q21 | Plug setting of a electromagnetic relay can be altered by varying
  • Number of ampere turns
  • Air gap of magnetic path
  • Adjustable back stop
  • None of these
Answer: Number of ampere turns
Q22 | Which material is used for the manufacture of bus bars?
  • Aluminium rods.
  • Copper rods.
  • Any conducting material.
  • Made of silver.
Answer: Copper rods.
Q23 | Which device sends the information to the circuit breaker to interrupt the circuitin case of fault?
  • Switch
  • Relay
  • Circuit breaker itself does this function.
  • Fuse.
Answer: Relay
Q24 | When does the circuit breaker operate in the line?
  • When power is to be supplie(D)
  • When the line is to be teste(D)
  • Whenever the fault occurs in the line.
  • Whenever the switch and the relay has to be operate(D)
Answer: Whenever the fault occurs in the line.
Q25 | What is the primary principle of a fuse?
  • Open the circuit.
  • Protect the appliance.
  • Protect the line.
  • Prevent excess current from flowing into the line.
Answer: Prevent excess current from flowing into the line.
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