### Testing And Commissioning Of Electrical Equipment’S Set 5

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
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
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
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.
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
Q6 | What should be the value of fusing factor?
• Equal to zero
• Equal to one
• Less than one
• More 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
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
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)
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.
Q11 | What is the cut off current in the fuse?
• Maximum value actually reache(D)
• Rms value actually reache(D)
• Average value actually reach
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
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
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
Q15 | Which among these tests are performed to check the nation or internationalstandards?
• Type test.
• Production tests.
• Site checks.
• All of the above.
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
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.
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.
Q19 | Which of the following circuit breakers has the lowest operating voltage?
• SF6 circuit breaker
• Air break
• Air blast
• Minimum oil circuit breaker
Q20 | The most efficient torque producing actuating structure for the induction typerelays is
• Watt hour meter structure
• Induction cup structure
• Single induction loop structure
Q21 | Plug setting of a electromagnetic relay can be altered by varying
• Number of ampere turns
• Air gap of magnetic path
• None of these
Q22 | Which material is used for the manufacture of bus bars?
• Aluminium rods.
• Copper rods.
• Any conducting material.
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.
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)
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.