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transmission and distribution MCQs

Practise focused transmission and distribution questions with marked answers for exam preparation and subject revision.

transmission and distribution Mcqs
1. Which of the following D.C. distribution system is the simplest and lowest in first cost ?
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A. Radial system

B. Inter-connected system

C. Ring system

D. None of the above

2. A conductor, due to sag between two supports, takes the form of____________?
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A. ellipse

B. triangle

C. catenary

D. semi-circle

3. The phenomenon qf rise in voltage at the receiving end of the open-circuited or lightly loaded line is called the________________?
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A. none of the above

B. Seeback effect

C. Ferranti effect

D. Raman effect

4. Galvanised steel wire is generally used as______________?
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A. all of the above

B. stay wire

C. earth wire

D. structural components

5. Which of the following materials is used for overhead transmission lines ?
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A. Any of the above

B. Cadmium copper

C. Galvanised steel

D. Steel cored aluminium

6. The use of strain type insulators is made where the conductors are__________?
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A. at intermediate anchor towers

B. any of the above

C. dead ended

D. none of the above

7. Which of the following bus-bar schemes has the lowest cost?
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A. Ring bus-bar scheme

B. Single bus-bar scheme

C. Main and transfer scheme

D. Breaker and a half scheme

8. The material generally used for armour of high voltage cables is_____________?
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A. aluminium

B. brass

C. steel

D. copper

9. Multicore cables generally use________________?
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A. sector-shaped conductors

B. rectangular conductors

C. circular conductors

D. square conductors

E. none of the above

10. Which of the following distribution systems is more reliable?
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A. All are equally reliable

B. Ring main system

C. Radial system

D. Tree system

11. A circuit is disconnected by isolators when____________?
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A. line is on full load

B. line is energized

C. circuit breaker is not open

D. there is no current in the line
12. The angular displacement between two interconnected stations is mainly due to___________?
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A. armature reactance of both alternators

B. reactance of the interconnector

C. synchronous reactance of both the alternators

D. all of the above

13. Which of the following equipment, for regulating the voltage in distribution feeder, will be most economical?
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A. Static condenser

B. Booster transformer

C. Synchronous condenser

D. Tap changing transformer

14. The current drawn by the line due to corona losses is___________?
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A. square

B. sinusoidal

C. triangular

D. non-sinusoidal
15. Overhead lines generally use__________________?
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A. all aluminium conductors

B. A.C.S.R. conductors

C. copper conductors

D. none of these

16. The material commonly used for insulation in high voltage cables is_______________?
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A. paper

B. rubber

C. lead

D. none of the above

17. The material commonly used for sheaths of underground cables is______________?
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A. rubber

B. iron

C. copper

D. lead
18. If variable part of annual cost on account of interest and depreciation on the capital outlay is equal to the annual cost of electrical energy wasted in the conductors, the total annual cost will be minimum and the corresponding size of conductor will be most economical. This statement is known as___________________?
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A. Ohms law

B. Faradays law

C. Kelvins law

D. Kirchhoffs law

E. none of the above

19. _______________are the conductors, which connect the consumers terminals to the distribution?
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A. Distributors

B. Service mains

C. Feeders

D. None of the above

20. For an overhead line, the surge impedance is taken as________________?
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A. 20-30 ohms

B. 7080 ohms

C. none of the above

D. 5001000 ohms

E. 100200 ohms
21. Which of the following is the demerit of a constant voltage transmission system ?
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A. Possibility of carrying increased power for a given conductor size in case of long-distance heavy power transmission

B. Increase of short-circuit current of the system

C. Availability of steady voltage at all loads at the line terminals

D. Improvement of power factor at times of moderate and heavy loads

E. Possibility of better protection for the line due to possible use of higher terminal reactants

22. Which of the following is usually not the generating voltage ?
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A. 13.2 kV

B. 11 kV

C. 8.8 kV

D. 6.6 kV

23. Which of the following characteristics should the line supports for transmission lines possess?
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A. All of the above

B. High mechanical strength

C. Low cost

D. Longer life

24. When the interconnector between two stations has large reactance?
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A. none of the above

B. the transfer of power will take place with voltage fluctuation and noise

C. the stations will fall out of step because of large angular displacement between the stations

D. the transfer of power will take place with least loss

25. Which of the following is not a constituent for making porcelain insulators ?
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A. Kaolin

B. Quartz

C. Felspar

D. Silica
26. The minimum clearance between the ground and a 220 kV line is about_________________?
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A. 4.3 m

B. 10.5 m

C. 5.5 m

D. 7.0 m
27. As compared to a 2-wire D.C. distributor, a 3-wire distributor with same maximum voltage to earth uses only__________________?
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A. 31.25 percent of copper

B. 66.7 percent of copper

C. 125 percent of copper

D. 33.3 percent of copper

28. In the analysis of which of the following lines shunt capacitance is neglected?
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A. Medium as well as long transmission lines

B. Short transmission lines

C. Long transmission lines

D. Medium transmission lines

29. Which of the following methods is used for laying of underground cables ?
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A. Solid system

B. All of the above

C. Draw-in-system

D. Direct laying

30. The skin effect of a conductor will reduce as the__________?
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A. permeability of conductor material increases

B. diameter increases

C. resistivity of conductor material increases

D. frequency increases

31. For aluminium, as compared to copper, all the following factors have higher values except:
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A. electrical conductivity

B. specific volume

C. resistance per unit length for same cross-section

D. co-efficient of linear expansion

32. By which of the following methods string efficiency can be improved?
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A. None of the above

B. Using a guard ring

C. Using long cross arm

D. Grading the insulator

E. Any of the above
33. Besides a method of trial and error, which of the following methods is employed for solution of network problems in interconnected system ?
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A. Circulating current method

B. Thevenins theorem

C. All of the above

D. Superposition of currents

E. Direct application of Kirehhoffs laws

34. Pin type insulators are generally not used for voltages beyond_________?
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A. 22 kV

B. 33 kV

C. 1 kV

D. 11 kV

35. The loads on distributors systems are generally__________________?
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A. none of the above

B. either of the above

C. unbalanced

D. balanced

36. The operating voltage of high voltage cables is up to_______________?
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A. llkV

B. 6.6kV

C. 3.3kV

D. l.lkV

37. In AC.S.R. conductors, the insulation between aluminium and steel conductors is_________?
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A. no insulation is required

B. varnish

C. bitumen

D. insulin

38. The frequency of voltage generated, in case of generators, can be increased by___________?
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A. using reactors

B. none of the above

C. reducing the terminal voltage

D. adjusting the governor

E. increasing the load

39. The voltage drop, for constant voltage transmission is compensated by installing__________?
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A. capacitors

B. synchronous motors

C. all of above

D. inductors

E. none of the above

40. When a live conductor of public electric supply breaks down and touches the earth which of the following will happen?
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A. None of the above

B. Supply voltage will increase

C. No current will flow in the conductor

D. Current will flow to earth

E. Supply voltage will drop

41. High voltage transmission lines use__________________?
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A. suspension insulators

B. pin insulators

C. both A. and B.

D. none of the above

42. On which of the following factors skin effect depends?
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A. Resistivity of the conductor material

B. All of the above

C. Size of the conductor

D. Frequency of the current

43. The steel used in steel cored conductors is usually__________?
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A. mild steel

B. alloy steel

C. stainless steel

D. all of the above

E. high speed steel

44. The operating voltage of extra high tension cables is upto_______________?
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A. 33 kV

B. 66 kV

C. 6.6 kV

D. 11 kV

E. 132 kV

45. The spacing between phase conductors of a 220 kV line is approximately equal to________________?
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A. 8.5 m

B. 2 m

C. 6 m

D. 3.5 m

46. A uniformly-loaded D.C. distributor is fed at both ends with equal voltages. As compared to a similar distributor fed at one end only, the drop at the middle point is______________?
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A. one-third

B. one-half

C. none of the above

D. twice

E. one-fourth
47. The distributors for residential areas are______________?
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A. three-phase three wire

B. single phase

C. three-phase four wire

D. none of the above

48. For transmission of power over a distance of 200 km, the transmission voltage should be_________kv?
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A. 132 kV

B. 11 kV

C. 33 kV

D. 66 kV

49. When a conductor carries more current on the surface as compared to core, it is due to___________?
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A. corona

B. permeability variation

C. skin effect

D. none of the above

E. unsymmetrical fault

50. For which of the following equipment current rating is not necessary?
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A. Circuit breakers

B. Isolators

C. Load break switch

D. Circuit breakers and load break switches