Transmission & Distribution Objective Questions-2021



 

1. The material used for the manufacture of the ground wire is


(a) aluminum.
(b) galvanized steel.
(c) cast iron.
(d) stainless steel

Ans: (b) galvanized steel.

The term "ground" refers to a connection to the earth, which acts as a reservoir of charge. A ground wire provides a conducting path to the earth which is independent of the normal current-carrying path in an electrical appliance.

2.. Guy Wire is employed for


(a) providing protection against surges.
(b) providing emergency earth route.
(c) Supporting the pole. 
(d) all of the above.

Ans: (c) Supporting the pole. 

3. The sag of a transmission line is least affected owing to

 
(a) weight of the conductor.
(b) current through the conductor.
(c) atmospheric temperature.
(d) ice deposition on the conductor.

Ans: (b) current through the conductor.


4. Effect of temperature rise in overhead lines is to


(a) increase the sag and decrease the tension.
(b) decrease the sag and increase the tension.
(c) increase both.
(d) decrease both 


Ans: (a) increase the sag and decrease the tension.

5. The sag of a transmission line conductor in summer is


(a) less than that in winter. 
(b) more than that in winter.
(C) same as in winter. 

Ans: (b) more than that in winter.

6. In a transmission line, sag depends upon


(a) span length.
(b) tension in conductors.
(C) weight of the conductor per unit length.
(d) all of the above.

Ans: (d) all of the above.


7. Which of the following statements is correct?


(a) Ice on conductors increases skin effect.
(b) pressure reduces the corona effect.
(c) pressure is taken to act at perpendicular to that for ice.
(d) Ice on conductors reduces sag.


Ans: (c) pressure is taken to act at perpendicular to that for ice.

8. Wind loading in coastal regions is in


(a) 40-50 kg/m
(b) 150 kg/m2
(c) 96 kg/m2

Ans: (b) 150 kg/m2


9. The maximum tension in a section of the overhead line conductor between two supports of unequal height occurs at


(a) the higher support.
(b) the lower point.
(c) the midpoint of the conductor.
(d) None of the above.

Ans: (a) the higher support.


10. Stringing chart is useful


(a) for finding the sag in the conductor.
(b)in the design of tower.
(c) in the design of insulator string.
(d) finding the distance between towers.

Ans: (a) for finding the sag in the conductor.

11. Hot template curves are plots of


(a) temperature and humidity.
(b) conductor sag and span lengths.
(c) conductor weight and sag.
(d) none of the above.

Ans: (b) conductor sag and span lengths.


12. The effect of wind pressure is more predominant on


(a) insulators.
(b) transmission lines.
(c) supporting lowers. 
(d) none of the above.

Ans: (c) supporting lowers. 


13. Galloping in transmission line conductors arises due to


(a) asymmetrical layers of ice formation.
(b) vortex phenomenon in light winds.
(c)  heavy weight of the line conductors.
(d) adoption of horizontal conductor configuration.


Ans: (a) asymmetrical layers of ice formation.


14. Which one of the following is reduced by using stock bridge dampers on power overhead transmission lines?

(a) Sag
(b) Conductor vibration.
(c) Line losses.
(d) Mechanical tension.

Ans: (b) Conductor vibration.


15. The sag of the conductors of a transmission line is 2.5 m when the span is 250 m. Now if the height of the supporting tower is increased by 25%, the sag will

(a) reduce by 25%
(b) increase by 25%
(c) reduce by 12.5%
(d) remain unchanged.

Ans: (d) remain unchanged.

16. For a 400 kV line, the spacing between phase conductors is around

(a) 8 m. 
(b) 11 m. 
(c) 14 m. 
(d) 17 m.

Ans: (a) 8 m. 



17. Stranded conductors usually have a central wire around which there are successive layers of 6,12,18,24 wires. For n-layers, the total number of individual wires is

(a) 3 n (n + 1)
(b) 2n (n + 1)
(c) 3 n(n + 1) + 1 
(d) 2 n (n + 1) + 1

Ans: (c) 3 n(n + 1) + 1 

18. The diameter of each strand is d then the diameter of n-layer the stranded conductor will be

(a) (2 n + 1) d
(b) 3 (n + 1) d
(c) (2n-1)d
(d) 3 (n-1)d

Ans: (a) (2 n + 1) d


19. Strain type insulators are used

(a) at dead ends.
(b) at intermediate anchor towers.
(c) on straight runs, 
(d) any of (a) or (b).

Ans: (d) any of (a) or (b).

20. Wavy structure of pin insulator increases its

(a) mechanical strength, 
(b) puncture strength
(c) flash-over voltage. 
(d) thermal strength.

Ans: (c) flash-over voltage. 

21. The voltage rating of a multiple shell (petticoat or rainshed) pin type insulator unit cannot be increased beyond a limiting value by increasing the number of shells, because

(a) the internal voltage distribution between shells becomes unequal.
(b) the leakage path resistance starts diminishing.
(c) the disruptive critical voltage for the material of the insulator is reached.
(d) the puncture voltage of the material of the insulator is reached

Ans: (a) the internal voltage distribution between shells becomes unequal.



22. Which type of insulators are used on 132 kV transmission lines ?

(a) Pin type.
(b) Disc type.
(C) Shackle type.
(d) Pin and Shackle

Ans: (b) Disc type.


23. Whenever the conductors are dead-ended or there is a change in the direction of the transmission line, the insulators used are of the type.

(a) Pin Type.
(b) Suspension type
(c) Strain type.
(d) Shackle type

Ans: (c) Strain type.


24. Post type insulators are generally used in lines operating

(a) above 100 KV.
(b) below 33 kV.
(c) at any voltage level, hv or ehv.

Ans: (c) at any voltage level, hv or ehv.

25. The number of discs in a string of insulators for 400 kV ac overhead transmission line lies in the range of

(a) 32 to 33 
(b) 22 to 23 
(c) 15 to 16 
(d) 9 to 10

Ans: (b) 22 to 23 

 
26. The non-uniform distribution of voltage across the units in a string of suspension type insulators is due to
(a) unequal self-capacitance of the units.
(b) non-uniform distance of separation of the units from the tower body
(c) the existence of stray capacitance between the metallic junctions of the units and the tower body
(d) non-uniform distance between the cross-arms and the units.

Ans: (c) the existence of stray capacitance between the metallic junctions of the units and the tower body



27. The voltages across the various discs of a string of suspension insulators having identical discs is different due to
(a) surface leakage currents. 
(b) series capacitance.
(C) shunt capacitance to ground.
(d) series and shunt capacitances. 

Ans: (C) shunt capacitance to ground.

28. The string efficiency of a string of suspension insulators is dependent on
(a) size of the insulators. 
(b) number of discs in the string.
(c) size of tower.

Ans:(b) number of discs in the string.

 
29. 100 per cent string efficiency means
(a) one of the insulator discs shorted.
(b) zero potential across each disc.
(c) equal potential across each insulator disc.
(d) none of the above.

Ans: (c) equal potential across each insulator disc.


30. In a suspension type insulator, the potential drop is
(a) maximum across the lowest disc.
(b) the maximum across the topmost disc.
(c) uniformly distributed over the discs.

Ans: (a) maximum across the lowest disc.



31. If the frequency of a transmission system is changed from 50 Hz to 100 Hz, the string efficiency
(a) will increase.
(b) will decrease.
(c) remain unchanged.
(d) may increase or decrease depending on the line parameters.

Ans: (c) remain unchanged.


32. The string efficiency of a high-voltage line is around
(a) 100% 
(b) 80%
(c) 40% 
(d) 10%

Ans: (b) 80%

33. The ratio of puncture voltage to the flash-over voltage of a line insulator is
(a) equal to 1
(b) lower than 1
(c) much greater than 1

Ans: (c) much greater than 1

 
34. The insulators may fail due to
(a) flashover.
(b) short-circuits.
(c) deposition of dust. 
(d) any of the above.

Ans: (d) any of the above.

35. The purpose of the guard ring in transmission lines is to
(a) reduce the earth capacitance of the lowest unit.
(b) increase the earth capacitance of the lowest unit.
(c) reduce the transmission line losses.
(d) none of the above.

Ans: (a) reduce the earth capacitance of the lowest unit.


36. The use of a guard ring
(a) equalizes the voltage division between insulator discs.
(b) is an unnecessary complication.
(c) decreases string efficiency.

Ans: (a) equalizes the voltage division between insulator discs.


37. Corona is
(a) partial breakdown of air. 
(b) a complete breakdown of air.
(c) sparking between lines. 

Ans: (b) a complete breakdown of air.

38. Which of the following statements is true regarding corona?
(a) Corona takes place at a voltage lower than breakdown voltage.
(b) Corona takes place at a voltage higher than breakdown voltage.
(c) Corona is a current phenomenon.
(d) Corona increases the transmission line efficiency.

Ans:(a) Corona takes place at a voltage lower than breakdown voltage.


39. Corona is accompanied by
(a) violet visible discharge in darkness
(b) hissing sound. 
(c) vibration
(d) power loss.
(e) radio interference.
(f) ozone
(g) all of the above.

Ans: (g) all of the above.

40. Ozone effect can be detected by
(a) presence of ozone detected by odor.
(b) hissing sound.
(c) faint luminous glow of bluish color.
(d) all of the above.

Ans: (d) all of the above.



41. Corona loss increases with
(a) decrease in conductor size and increase in supply frequency.
(b) increase in both conductor size and supply frequency.
(c) decrease in both conductor size and supply frequency
(d) increase in conductor size and decrease in supply frequency

Ans: (a) decrease in conductor size and increase in supply frequency.



42. The good effect of corona on overhead lines is to
(a) increase the line carrying capacity due to conducting ionised air envelopes around the conductor.
(b) increase the power factor due to corona loss.
(c) reduce the radio interference from the conductor.
(d) reduce the steepness of surge fronts. 

Ans: (d) reduce the steepness of surge fronts. 

43. Compared with a solid conductor of the same radius, corona appears on a stranded conductor at a lower voltage, because stranding
(a) assists ionization.
(b) makes the current flow spirally about the axis of the conductor.
(c) produces oblique sections to a plane perpendicular to a axis of the conductor
(d) produces surfaces of smaller radius. 

Ans: (d) produces surfaces of smaller radius.


44. Corona loss can be reduced by the use of hollow conductors because
(a) the current density is reduced.
(b) the eddy current in the conductor is eliminated.
(c) for a given cross-section, the radius of the conductor is
increased
(d) of better ventilation in the conductor.

Ans:(c) for a given cross-section, the radius of the conductor is
increased

45. Bundled conductors reduce
(a) surface electric stress of conductor.
(b) increases the line reactance.
(c) decreases the line capacitance.

Ans:(a) surface electric stress of conductor.


46. Corona loss in a transmission line is dependent on
(a) the diameter of the conductor.
(b) material of the conductor.
(c) height of the conductor.

Ans:(a) the diameter of the conductor.

47. Corona occurs between two transmission conductors when they
(a) have high potential difference. 
(b) are closely spaced,
(c) carry the power.
(d) both (a) and (b)

Ans:(d) both (a) and (b)


48. In humid weather, the corona occurs at a voltage
(a) much less than that needed in fair weather.
(b) much higher than that needed in fair weather.
(c) equal to that needed in fair weather,
(d) none of the above.

Ans:(a) much less than that needed in fair weather.

49. The effect of corona is
(a) increased energy loss. 
(b) increased reactance.
(c) increased inductance. 
(d) all of the above.

Ans: (a) increased energy loss. 


50. The charging current in a transmission line increases due to corona effect because corona increases
(a) linc current.
(b) effective line voltage.
(c) power loss in lines. 
(d) the effective conductor diameter.

Ans:(d) the effective conductor diameter.


51. The chances of occurrence of corona are maximum during
(a) humid weather. 
(b) dry weather.
(c) winter.
(d) hot summer.

Ans:(a) humid weather. 


52. Corona is likely to occur maximum in case of
(a) distribution lines. 
(b) transmission lines.
(c) domestic wiring. 
(d) service mains.

Ans: (b) transmission lines.


53. Corona is affected by
(a) size of conductor.
(b) shape and surface condition of the conductor,
(c) operating voltage. 
(d) all of the above.

Ans: (d) all of the above.


54. The only advantage of corona is that it
(a) produces a pleasing luminous glow,
(b) makes line current sinusoidal.
(c) works as a safety valve for surges,
(d) ozone gas is produced,

Ans:(c) works as a safety valve for surges,


55. The presence of ozone owing to corona
(a) improves the pl. 
(b) reduces the pf.
(c) corrodes the material,
(d) improves regulation

Ans: (c) corrodes the material,

56. What is the approximate breakdown strength of atmospheric air an NT.P.?
(a) 0.3 kV/cm
(b) 1.0kV/cm.
(c) 3 kV/cm.
(d) 30 kV/cm.

Ans:(d) 30 kV/cm.

57. The dielectric strength of air under normal condition is about
(a) 100 KV/cm
(c) 30 kV cm
(b) 21.1 kV/cm
(d) 200 kV/cm

Ans: (b) 21.1 kV/cm

 
58. Disruptive corona begins in smooth cylindrical conductors in air at NTP if the electric field intensity at the conductor surface goes up to
(a) 21.1 kV (rms)/cm. 
(b) 21.1 kV (peak)/cm.
(C) 21.1 kV (average)/cm 
(d) 21.1 kV (rms/m.

Ans:(a) 21.1 kV (rms)/cm. 


59. The dielectric strength of air is
(a) proportional to barometric pressure.
(b) proportional to absolute temperature.
(c) inversely proportional to barometric pressure.
(d) none of the above.

Ans:(a) proportional to barometric pressure.


60. Visual critical voltage is
(a) lower than disruptive critical voltage.
(b) higher than disruptive critical voltage.
(c) equal to critical voltage. 
(d) none of the above.

Ans:(b) higher than disruptive critical voltage.



61. Skin effect exists in
(a) cable carrying de current 
(b) dc transmission line only
(c) ac transmission line only.
(d) dc as well as ac transmission lines.

Ans: (c) ac transmission line only.

62. Skin effect in a conductor becomes more pronounced
(a) at higher frequency 
(b) at lower frequency
(c) at dc.

Ans: (a) at higher frequency 

63. The skin effect in conductor results in
(a) increases in its dc resistance. 
(b) decrease in its ac resistance.
(c) increase in its ac resistance.

Ans:  (c) increase in its ac resistance.

64. Skin effect 
(a) increases the effective resistance and effective internal reactance.
(b) reduces the effective resistance and effective internal reactance.
(c) increases the effective resistance but reduces the effective internal reactance.
(d) reduces the effective resistance but increases the effective internal reactance.

Ans: (c) increases the effective resistance but reduces the effective internal reactance.


65. The skin effect of a conductor reduces with the increase in
(a) supply frequency
(b) resistivity of the conductor material.
(c) X-section of conductor
(d) permeability of conductor material.

Ans:(b) resistivity of the conductor material.


66. Skin effect in conductor is proportional to
(a) (diameter of conductor) 1/2 
(b) diameter of conductor.
(c) (diameter of conductor)2. 
(d) (diameter of conductor)4.

Ans: (c) (diameter of conductor)2.

67. In order to reduce the skin effect at UHF
(a) copper tubes with silver plating are used.
(b) copper rods with silver plating are used.
(c) anodised conductors are used.
(d) painted conductors are used.

Ans:(a) copper tubes with silver plating are used.

68. Critical voltage limit of a transmission line is increased by
(a) increasing the radius of the conductors
(b) increasing the spacing between conductors.
(c) reducing the spacing between conductors
(d) reducing the radius of the conductors.

Ans:(a) increasing the radius of the conductors

69. The maximum permissible value of fair weather corona loss for an HV line is
(a) 0.6 kW/3-phase km.
(c) 0.3 kW/3-phase km.
(b) 1.2 kW13-phase km.
(d) 24 kW/3-phase km.

Ans:(d) 24 kW/3-phase km. 



70. Corona losses are minimised when
(a) conductor size is reduced. 
(b) smooth conductor is used.
(c) sharp points are provided in the line hardware,
(d) current density in conductors is reduced.

Ans: (b) smooth conductor is used.

71. Corona loss can be reduced by using
(a) solid conductor of diameter d'.
(b) hollow conductor of diameter d + rowd'.
(c) bundle conductor. 
(d) both (a) and (b).
(e) both (b) and (c).

Ans: (e) both (b) and (c).

72. In a transmission line the distributed constants are
(a) resistance and shunt conductance only.
(b) resistance and inductance only.
(c) resistance, inductance and capacitance only.
(d) resistance, inductance, capacitance and shunt conductance.

Ans: (d) resistance, inductance, capacitance and shunt conductance.

73. Skin effect depends upon A,
(a) X-section of conductor. 
(b) supply frequency.
(c) permeability of conductor material
(d) all of the above,

Ans:(d) all of the above,

74. Skin effect in transmission line is due to
(a) supply frequency,
(b) self inductance of conductor
(c) high sensitivity of material in the centre.
(d) both (a) and (b).

Ans: (d) both (a) and (b).

75. The effective resistance of a conductor will be the same as ohmic resistance when
(a) voltage is low.
(b) current is true sinusoidal.
(c) current is uniformly distributed in the X-section of the conductor

Ans: (c) current is uniformly distributed in the X-section of the conductor

76. When an alternating current flows through a conductor
(a) entire current passes through the core of the conductor.
(b) portion of conductor near the surface carries more current in comparison to the core.
(c) current remains uniformly distributed over the whole x-section of the conductor.
(d) portion of conductor near the surface carries less current in comparison to the core.

Ans: (b) portion of conductor near the surface carries more current in comparison to the core.

77. The conductor carries more current on the surface in comparison to its core. This phenomenon is called the
(a) skin effect.
(b) corona.
(c) Ferranti effect.
(d) Lenz's effect.

Ans:(a) skin effect.

78. Increasing the frequency of transmission line will
(a) increase shunt reactance. 
(b) decrease line resistance.
(c) increase line resistance. 
(d) decrease series reactance.

Ans: (c) increase line resistance. 

79. Hollow conductors are used in transmission lines to
(a) reduce weight of copper. 
(b) improve stability.
(c) reduce corona.
(d) increase power transmission capacity.

Ans: (c) reduce corona.

80. Bundled conductors are employed to improve
(a) appearance of the transmission line.
(b) mechanical stability of the line.
(c) current canying capacity of the line.
(d) corona performance of the line.

Ans: (d) corona performance of the line.

81. In hv transmission, the spacing between subconductors of a bundle is approximately
(a) 20 cm 
(b) 40 cm 
(c) 80 cm
(d) 3.5 cm

Ans:(b) 40 cm 
 
82. For a stranded conductor, the ratio of GMR to actual radius is
(a) equal to 1.
(b) more than 1.
(c) equal to 0.7788. 
(d) less than 0.7788

Ans: (d) less than 0.7788
 
83. Bundled conductors in EHV transmission system provide
(a) reduced capacitance.
(b) increased capacitance.
(c) increased inductance. 
(d) increased voltage gradient

Ans: (b) increased capacitance.

84. Which one of the following statements is not correct for the use of bundled conductors in transmission lines?
(a) Control of voltage gradient.
(b) Reduction in corona loss.
(c) Reduction in radio interference.
(d) Increase in interference with communication lines.

Ans: (d) Increase in interference with communication lines.

85. Bundled conductors are mainly used in high voltage overhead transmission lines to
(a) reduce transmission line losses.
(b) increase mechanical strength of the line.
(c) reduce corona,
(d) reduce sag.

Ans: (c) reduce corona,

86. For equilateral spacing of conductors of an untransposed 3-phase line, we have
(a) balanced receiving-end voltage and no communication interference
(b) unbalanced receiving-end voltage and no communication interference.
(c) balanced receiving-end voltage and communication interference
(d) unbalanced receiving-end voltage and communication interference.

Ans: (d) unbalanced receiving-end voltage and communication interference.

87. Transmission lines are transposed to
(a) reduce corona loss 
(b) reduce skin effect
(c) prevent interference with neighbouring telephone lines.
(d) prevent short-circuit between any two lines,

Ans:(c) prevent interference with neighbouring telephone lines.

88. Transposition of transmission line is done to
(a) reduce line loss. 
(b) reduce skin effect.
(c) balance line voltage drop
(d) reduce corona. 

Ans: (c) balance line voltage drop

89. High voltage transmission lines are transposed because then
(a) corona losses can be minimized.
(b) computation of inductance becomes casier
(c) voltage drop in the lines can be minimized
(d) phase voltage imbalances can be minimized.

Ans: (d) phase voltage imbalances can be minimized.

90. The concept of an electrically short, medium and long line is primarily based on the
(a) nominal voltage of the line. 
(b) physical length of the line
(c) wavelength of the line
(d) power transmitted over the line.

Ans: (b) physical length of the line
 
91. Equivalent A model is quite suitable for analyzing the performance of transmission line of
(a) 50 km length
(b) 150 km length
(c) 250 km length
(d) All of the above lengths.

Ans:  (c) 250 km length

92. Which of the following is neglected while analysing a short transmission line
(a) Shunt admittances. 
(b) Power losses
(c) Series impedance.
(d) None of the above.

Ans: (a) Shunt admittances. 

93. Capacitance in equivalent circuit of a transmission line is due to
(a) current in the line.
(b) difference in potential of line,
(c) leakage of current.
(d) presence of magnetic flux.

Ans: (b) difference in potential of line,

94. If the separation between the three phases of a transmission line is increased then
(a) the inductance will increase and capacitance will remain unchanged.
(b) both the inductance and capacitance will increase.
(c) the inductance will increase and the capacitance will decrease.
(d) the inductance will decrease and the capacitance will increase.

Ans: (c) the inductance will increase and the capacitance will decrease.

96. Bundled conductors are used to
(a) reduce inductance of the line.
(b) reduce both inductance and capacitance.
(c) reduce corona loss.
(d) reduce corona loss and the line inductance.

Ans: (d) reduce corona loss and the line inductance.


97. Proximity of a line to the earth surface
(a) does not affect its capacitance to neutral
(b) increases the capacitance to neutral.
(c) decreases the capacitance to neutral.

Ans: (b) increases the capacitance to neutral.

98. If the effect of earth is taken into account, then the capacitance of
line to ground
(a) decreases.
(b) increases.
(c) remain unaltered
(d) becomes infinite.

Ans: (b) increases.

99. The inductance of single-phase two-wire power transmission line
per km gets doubled when the
(a) distance between the wires is doubled.
(b) distance between the wires is increased four fold.
(c) distance between the wires is increased as square of the original distance.
(d) radius of the wire is doubled. 

Ans: (c) distance between the wires is increased as square of the original distance.

100. Inductance of an overhead line, in comparison to that of a cable of same capacity is
(a) larger. 
(b) smaller. 
(c) of the same order.

Ans: (a) larger. 

101. For equilateral spacing of conductors of an untransposed 
3-phase line we have
(a) balanced receiving-end voltage and no communication
interference.
(b) unbalanced receiving-end voltage and no communication
interference.
(c) balanced receiving-end voltage and communication
interference,
(d) unbalanced receiving-end voltage and communication
interference

Ans: (d) unbalanced receiving-end voltage and communication
interference

102. Transmission lines are transposed to
(a) reduce corona loss.
(b) reduce skin effect.
(c) prevent interference with neighbouring telephone lines.
(d) prevent short-circuit between any two lines.

Ans: (c) prevent interference with neighbouring telephone lines.

103. Transposition of transmission line is done to
(a) reduce line loss. 
(b) reduce skin effect.
(c) balance line voltage drop.
(d) reduce corona. 

Ans: (c) balance line voltage drop.

104. High voltage transmission lines are transposed because then
(a) corona losses can be minimized.
(b) computation of inductance becomes easier.
(c) voltage drop in the lines can be minimized.
(d) phase voltage imbalances can be minimized.

Ans: (d) phase voltage imbalances can be minimized.

105. The concept of an electrically short, medium and long line is primarily based on the
(a) nominal voltage of the line. 
(b) physical length of the line.
(c) wavelength of the line.
(d) power transmitted over the line.

Ans: (b) physical length of the line.

106. The equivalent pie model is quite suitable for analyzing the performance of transmission line of
(a) 50 km length.
(b) 150 km length
(c) 250 km length. 
(d) All of the above lengths.

Ans: (c) 250 km length. 

107. Which of the following is neglected while analyzing a short
transmission line ?
(a) Shunt admittances. 
(b) Power losses.
(c) Series impedance. 
(d) None of the above.

Ans: (a) Shunt admittances. 

108. In modelling the equivalent circuit of a short length overhead
transmission line, the line resistance and inductance are only
considered because line capacitance to ground is
(a) equal to zero.
(b) finite but very small.
(C) finite but very large. 
(d) infinite.

Ans: (b) finite but very small.

109. Capacitance in equivalent circuit of a transmission line is due to
(a) current in the line 
(b) difference in potential of line.
(c) leakage of current 
(d) presence of magnetic flux.

Ans: (b) difference in potential of line.

110. If the separation between the three phases of a transmission line is increased then
(a) the inductance will increase and capacitance will remain unchanged.
(b) both the inductance and capacitance will increase
(c) the inductance will increase and the capacitance will decrease.
(d) the inductance will decrease and the capacitance will increase.

Ans: (c) the inductance will increase and the capacitance will decrease.

111. Bundled conductors are used to
(a) reduce inductance of the line.
(b) reduce both inductance and capacitance.
(c) reduce corona loss.
(d) reduce corona loss and the line inductance.

Ans: (d) reduce corona loss and the line inductance.

112. Proximity of a line to the earth surface
(a) does not affect its capacitance to neutral.
(b) increases the capacitance to neutral.
(c) decreases the capacitance to neutral.

Ans: (b) increases the capacitance to neutral.

113. If the effect of earth is taken into account, then the capacitance of line to ground
(a) decreases.
(b) remains unaltered.
(c) increases
(d) becomes infinite.

Ans: (c) increases

114. Proximity effect
(a) is more pronounced for large conductors, high frequencies and close proximity.
(b) increases the resistance of the conductors and reduces the self reactance.
(c) is substantially eliminated with stranded conductors.
(d) all of the above.

Ans: (d) all of the above.

115. The inductance of a power transmission line increases with
(a) decrease in line length.
(b) increase in diameter of conductor.
(c) increase in spacing between the phase conductors.
(d) increase in load current carried by the conductors.

Ans:(c) increase in spacing between the phase conductors.
 
116. The inductance of a transmission line is minimum when
(a) GMD is high.
(b) GMR is high.
(c) both GMD and GMR are high.
(d) GMD is low and GMR is high.

Ans: (d) GMD is low and GMR is high.

117. Hollow conductors are used in transmission lines to
(a) reduce weight of copper. 
(b) improve stability.
(c) reduce corona.
(d) increase power transmission capacity.

Ans:(c) reduce corona.

118. Bundled conductors are employed to improve
(a) appearance of the transmission line.
(b) mechanical stability of the line.
(c) current carrying capacity of the line.
(d) corona performance of the line.

Ans:(d) corona performance of the line.

119. In hv transmission, the spacing between subconductors of a bundle is approximately
(a) 20 cm 
(b) 40 cm 
(c) 80 cm
(d) 3.5 cm

Ans:(b) 40 cm 

120. For a stranded conductor, the ratio of GMR to actual radius is
(a) equal to 1.
(b) more than 1.
(c) equal to 0.7788. 
(d) less than 0.7788

Ans: (d) less than 0.7788

121. Bundled conductors in EHV transmission system provide
(a) reduced capacitance. 
(b) increased capacitance.
(c) increased inductance. 
(d) increased voltage gradient.

Ans: (b) increased capacitance.

122. Which one of the following statements is not correct for the use of bundled conductors in transmission lines?
(a) Control of voltage gradient.
(b) Reduction in corona loss.
(c) Reduction in radio interference.
(d) Increase in interference with communication lines.

Ans: (d) Increase in interference with communication lines.




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