Switch Gear and Protection 2

Lets Crack Online Exam

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


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