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Saturday, 8 October 2016

Distribution of Electric Power - Multiple Choice Questions

Distribution of Electric Power - Multiple Choice Questions Points : distribution of electric power, multiple choice questions and answers, electrical objective type question answers, mcqs 1. In the interconnected system, the reserve capacity of the system
(i) remains same
(ii) decreases
(iii) increases
(iv) none of above

2. As compared to overhead system, the underground system
(i) is more costly
(ii) has less chances of faults
(iii) has more useful life
(iv) all above

3. In primary distribution lines, the earth wire is placed
(i) above the phase conductors
(ii) below the phase conductors
(iii) inbetween the phase conductors
(iv) none of above

4. As compared to underground system, the overhead system is
(i) more expensive
(ii) less flexible
(iii) more flexible
(iv) none of above

5. The major part of investment on secondary distribution is made on
(i) conductors
(ii) poles
(iii) distribution transformers
(iv) none of above

6. In a 3-phase, 4-wire a.c. system, unbalancing is caused due to the connection of
(i) single-phase loads
(ii) 3-phase induction motors
(iii) synchronous condenser
(iv) none of above

7. The bulk power consumers are supplied at
(i) 66kV
(ii) 11kV
(iii) 230 kV
(iv) 33 kV

8. A 3-wire d.c. distribution system makes available
(i) one voltage
(ii) two voltages
(iii) three voltages
(iv) none of above

9. The voltage drop is the main consideration while designing a
(i) feeder
(ii) distributor
(iii) service mains
(iv) none of above

10. In a 3-wire d.c. system, the current in +ve outer is 200 A and in the —ye outer is 100 A. The current in the neutral wire is
(i) 100A
(ii) 200A
(iii) 300 A
(iv) 0 A

11. Grading of cables is carried out to
(i) achieve economy
(ii) reduce overall cable diameter
(iii) have uniform stress distribution
(iv) all above

12. The distribution transformer is generally connected in
(i) Delta/Delta
(ii) Delta/Star
(iii) Star/Star
(iv) Star/Delta

13. A line which connects a consumer to the distributor is called
(i) feeder
(ii) distributor
(iii) service mains
(iv) none of above

14. The minimum dielectric stress in a cable is at
(i) conductor surface
(ii) centre of conductor
(iii) lead sheath
(iv) none of above

15. The most reliable distribution system is
(i) interconnected system
(ii) radial system
(iii) ring main system
(iv) none of above

16. An a.c. secondary distribution system employs
(i) 11 kV, 3-phase, 3-wire system
(ii) 66 kV, 3-phase, 3-wire system
(iii) 33 kV, 3-phase, 3-wire system
(iv) 400/230 V 3-phase, 4-wire system

17. Which of the following distribution system is used for combined power and lighting loads?
(i) 1-phase, 2-wire a.c. system
(ii) 3-phase, 3-wire a.c. system
(iii) 3-phase, 4-wire ac. system
(iv) none of above

18. A line which connects distributor to substation is called
(i) service mains
(ii) distributor
(iii) feeder
(iv) none of above

19. When the length of a cable increases, its capacitance
(i) decreases
(ii) increases
(iii) remains same
(iv) none of above

20. The most common fault in overhead distribution system is
(i) phase to phase fault
(ii) one phase to earth fault
(iii) all phases short-circuited
(iv) none of above

21. The cable fault may be due to
(i) break in conductor
(ii) failure of insulation between conductors
(iii) failure of insulation between conductor and earth
(iv) all above

22. In a 3-wire d.c. system, the area of cross-section of neutral wire is generally
(i) half that of outers
(ii) double that of outers
(iii) same as that of outers
(iv) none of above

23. A line from which loath are tapped off is called
(i) feeder
(ii) distributor
(iii) service mains
(iv) none of above

24. The interconnected distribution system is more reliable because of the use of
(i) heavy size of conductor
(ii) two or more sources of supply
(iii) higher load current
(iv) none of above

25. Insulating material for cables should have
(i) high insulation resistance
(ii) high dielectric strength
(iii) high mechanical strength
(iv) all above

26. The domestic load that has unity power factors is
(i) fan
(ii) mixer
(iii) tube
(iv) filament lamp

27. The distribution transformer is rated in
(i) kW
(ii) kVAR
(iii) kVA
(iv) none of above

28. In a.c. motors, the magnetising current
(i) lags the voltage by 90°
(ii) leads the voltage by 90°
(iii) is in phase with voltage
(iv) none of above

29. The low lagging power factor in ac. Power system is due to
(i) induction motors
(ii) arc lamps
(iii) varying load on the system
(iv) all above

30. Voltage of primary distribution system is
(i) 400V
(ii) 33kV
(iii) 230V
(iv) 11kV

31. The low lagging power factor results in
(i) large copper losses
(ii) poor voltage regulation
(iii) reduced handling capacity
(iv) all above

32. Which of the distribution system is used for domestic loads?
(i) 3-phase, 3-wire system
(ii) 1-phase, 2-wire system
(iii) 3-phase, 4-wire system
(iv) none of above

33. The tine voltage on the L.T. side of a distribution transformer is
(i) 400V
(ii) 230V
(iii) 11 kV
(iv) 800 V

34. The ring main system is used in power distribution because it
(i) is reliable for continuity of supply
(ii) gives better voltage regulation
(iii) results in less feeder losses
(iv) all above

35. The requirement of a good distribution system is
(i) proper voltage
(ii) availability of power on demand
(iii) reliability
(iv) all above

36. Sheaths are used in cables to
(i) provide proper insulation
(ii) prevent ingress of moisture
(iii) provide mechanical strength
(iv) none of above

37. As compared to overhead system, the maintenance cost of underground system is
(i) very high
(ii) about the same
(iii) very low
(iv) none of above

38. Which of the distribution system is used for domestic loads?
(i) 3-phase. 4-wire system
(ii) 1-phase, 2-wire system
(iii) 3-phase, 3-wire system
(iv) none of above

39. The current in the radial distributor will be maximum at the
(i) source end of the distributor
(ii) midpoint of the distributor
(iii) end point of the distributor
(iv) none of above

40. The voltage in a radial distributor will be minimum at
(i) the distribution substation
(ii) the midpoint of the distributor
(iii) the end of the distributor
(iv) none of above

41. For operating voltages beyond 66 kV, the cables used are
(i) belted type
(ii) S.L. type
(iii) oil-filled
(iv) none of above

42. For the same safe potential, the size of a graded cable is
(i) less than non-graded cable
(ii) more than non-graded cable
(iii) same as for non-graded cable
(iv) none of above

43. The radial system of power distribution is used for
(i) short distances only
(ii) long distances only
(iii) both short and long distances
(iv) none of above

44. In capacitance grading of cables, the dielectric of highest permittivity is
(i) near the core
(ii) in the middle
(iii) farthest away from core
(iv) none of above

45. in a.c. system, additions and subtractions of currents are done
(i) vectorially
(ii) arithmetically
(iii) both (i) and (ii)
(iv) none of above

46. Which of the distribution system is used for balanced loads?
(i) 1-phase, 2-wire system
(ii) 3-phase, 4-wire system
(iii) 3-phase, 3-wire system
(iv) none of above

47. Power distribution by cables is generally adopted for line length
(i) less than 10 km
(ii) above 100 km
(iii) less than 50 km
(iv) above 200 km

48. In the event of fault, the line can by opened quickly by
(i) circuit breaker
(ii) Fuse
(iii) G.O. switch
(iv) all above

49. As the thickness of the insulation of a cable increases, its capacitance
(i) decreases
(ii) increases
(iii) remains same
(iv) none of above

50. In capacitance grading of cables, we use
(i) one dielectric
(ii) a large number of dielectrics
(iii) two or three dielectrics
(iv) none of above

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