Switch Gear and Protection 2

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Electrical Engineering MCQ Question Papers: Campus Placement

Subject: Switch Gear and Protection 2

Part 2: List for questions and answers of Switch Gear and Protection

 

Q1. What is switchgear?

a) An apparatus used for switching, controlling and protecting the electrical circuits and equipments

b) It detects the faults only

c) It corrects the faults only

d) All of the above

 

Q2. What is the primary principle of a fuse?

a) Open the circuit

b) Protect the appliance

c) Protect the line

d) Prevent excess current from flowing into the line

 

Q3. When does the circuit breaker operate in the line?

a) When power is to be supplied

b) When the line is to be tested

c) Whenever the fault occurs in the line

d) Whenever the switch and the relay has to be operated

 

Q4. Which device sends the information to the circuit breaker to interrupt the circuit in case of fault?

a) Switch

b) Relay

c) Circuit breaker itself does this function

d) Fuse

 

Q5. Which material is used for the manufacture of bus bars?

a) Aluminium rods

b) Copper rods

c) Any conducting material

d) Made of silver

 

Q6. How is the bus bars rated?

a) Current only

b) Voltage only

c) Current, voltage and frequency

d) Current, voltage, frequency and short circuit current 

 

Q7. Which among these are the main characteristics of a fuse element?

a) Low melting point

b) High conductivity

c) Least deterioration due to oxidation

d) All of the above

 

Q8. Which among the following statement is true related to fuse?

a) Greater the current smaller is the time taken by the fuse to blow out

b) Greater the current greater is the time taken by the fuse to blow out

c) The current is directly proportion to the blow out time of fuse

d) Is dependent on the temperature and atmospheric conditions

 

Q9. Which among these is the least expensive protection for over current in low voltage system?

a) Rewirable fuse

b) Isolator

c) Circuit breaker

d) Air breaker switch

 

Q10. For a current upto 10A which material is used as the fusing element?

a) Copper

b) Silver

c) Alloy of lead and tin

d) Zinc

 

Q11. What is the relation between the fusing current and the diameter of the wire?

a) I=kd3

b) I=kd3/2

c) I=kd2

d) I=kd2/3

 

Q12. What is fusing factor?

a) The ratio of current rating of the fuse to the minimum fusing current

b) The ratio of minimum fusing current to the current rating of the fuse

c) The ratio of maximum fusing current to the current rating of the fuse

d) The ratio of minimum fusing current to the voltage rating of the fuse 

 

Q13. What should be the value of fusing factor?

a) Equal to zero

b) Equal to one

c) Less than one

d) More than one

 

Q14. What is the maximum current upto which fuses can be used?

a) 25 A

b) 50 A

c) 75 A

d) 100 A

 

Q15. What is the typical value of the pre arcing time?

a) 0.1

b) 0.01

c) 0.001

d) 0.0001

 

Q36. A fuse wire of circular cross section has a radius of 0.8mm. The wire blows off at a current of 9A. What will be the radius of the wire that will blow off at a current of 1A?

a) 0.2 mm

b) 0.18 mm

c) 0.28 mm

d) 0.3 mm

 

Q17. Which among these tests are performed to check the nation or international

standards?

a) Type test

b) Production tests

c) Site checks

d) All of the above

 

Q18. If the strands of the fusing wire are twisted, what happens to the fusing current?

a) Increases

b) Reduces

c) No change/ remains same

d) Depends on the value of current, increases or decreases 

 

Q19. What is the cut off current in the fuse?

a) Maximum value actually reached

b) Rms value actually reached

c) Average value actually reached

d) None of the above

 

Q20. What is the advantage of HRC fuses over Rewirable fuses?

a) High speed operation

b) High rupturing capacity

c) No ageing effect

d) All of the above 

 

Part 2: List for questions and answers of Switch Gear and Protection

 

Q1. Answer: d

 

Q2. Answer: d

 

Q3. Answer: c

 

Q4. Answer: b

 

Q5. Answer: b

 

Q6. Answer: c

 

Q7. Answer: d

 

Q8. Answer: a

 

Q9. Answer: a

 

Q10. Answer: c

 

Q11. Answer: b

 

Q12. Answer: b

 

Q13. Answer: c

 

Q14. Answer: d

 

Q15. Answer: b

 

Q16. Answer: b

 

Q17. Answer: a

 

Q18. Answer: b

 

Q19. Answer: a

 

Q20. Answer: d