ENGINEERS ACADEMY Questions Bank EE... · surge impedance loading (a) The receiving- end voltage is...

58 | Modelling of Transmission Line Junior EngineerENGINEERS ACADEMY

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1. The effect of capacitance can be neglectedwhen the length of overhead transmission linedoes not exceed(a) 20 km (b) 60 km(c) 120 km (d) 300 km

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

3. For a 500 Hz frequency excitation, a 50km longpower line will be modelled as(a) Short line.(b) Medium line(c) Long line(d) Data insufficient for decision

4. Percentage regulation of a short transmission lineis given by the expression

(a)R S

R

V V 100V

(b)R S

S

V V 100V

(c)S R

R

V V 100V

(d)S R

S

V V 100V

5. As compared to sending-end voltage, the receiving-end voltage of a short line under no-load conditionis(a) higher(b) Lower(c) Remains the same(d) None of these

6. If a short transmission line is delivering to laggingpf load, the sending-end pf would be (notationshaving their usual meaning)

(a)R

S

V cos IR sinV

(b)R

S

V cos IRV

(c)R

S

V sin IRV

(d)R

S

V sin IR cosV

7. Which of the following voltage regulation isconsidered to be the best

(a) 2% (b) 30%

(c) 70% (d) 98%

8. A short transmission line, having its line impedanceangle as , is delivering a given power at thereceiving end at a lagging power factor angle of .Which one of the following is a set of conditionsfor which this line will have maximum and zeroregulation?

Maximum regulation Zero Regulation

(a) = – = 2

(b) –2

=

(c) = 2

(d)2

=

QUESTION BANK

ENGINEERS ACADEMY



EE : Power Systems Modelling of Transmission Line | 599. For a short line if the receiving-end voltage is =

sending end voltage under loaded conditions(a) The sending-end power factor is unity(b) The receiving-end power factor is unity(c) The sending-end power factor is leading(d) The receiving-end power factor is leading

10. The regulation of a line at full load 0.8 pf lagging is12%. The regulation at full-load 0.8 pf leading can be(a) 24% (b) 18%(c) 12% (d) 4%

11. If in a short transmission line, resistance andinductive reactance are found to be equal andregulation appears to be zero, then the load will(a) Have unity power factor(b) Have zero power factor(c) be 0.707 leading(d) None of these

12. A single phase transmission line of impedance j 0.8ohm supplies a resistive load of 500 A at 300 V.The sending-end power factor is(a) Unity (b) 0.8 lagging(c) 0.8 leading (d) 0.6 lagging

13. For an ac transmission line of length not exceeding80 km, it is usual to lump the line capacitance at(a) The sending end (b) The receiving end(c) The mid point (d) Any convenient point

14. If L, C and Y are the inductance, capacitance andshunt admittance of a line per unit length, then forlength l.(a) The shunt admittance is Y.l.(b) The inductance is L/l(c) The capacitance C/l(d) The shunt admittance is Y/l

15. Transmission efficiency of a transmission lineincreases with the(a) Decrease in power factor and voltage(b) Increase in power factor and voltage(c) Increase in power factor but decrease in voltage(d) Increase in voltage but decrease in power factor

16. Consider two parallel short transmission lines ofimpedances ZA and ZB respectively. Currents IAand IB are both lagging and the sending-end voltageis VS. If the reactance to resistance ratio of boththe impedances ZA and ZB are equal, then the totalcurrent I will(a) lag both IA and IB

(b) lead both IA and IB

(c) Lag one of IA and IB but lead the other(d) Be phase with Both IA and IB

17. Under no load consitions, the current in atransmission line is because of(a) Capacitance effect(b) Corona effect(c) Proximity effect(d) Back flow from earth

18. Charging current in transmission line(a) Reduces the line losses(b) Increases the line losses(c) Will not affect the line losses(d) Unpredictable

19. Which of the following statements are correct?(a) Flow of unduly heavy current is Ferranti effect(b) Ferranti effect occurs under unloaded condition

of line.(c) The rise in receiving-end voltage is Ferranti

effect(d) Both (b) and (c) combined is Ferranti effect

20. The phenomenon of rise in receiving-end voltageof the open -circuited or lightly load line is calledthe(a) Proximity effect (b) Skin effect(c) Ferranti effect (d) Seeback effect

21. For a long distance hv transmission line thereceiving-end voltage under unloaded condition is(a) Much lower than(b) Lower than(c) Equal to(d) Higher than the sending-end voltage




22. In a long transmission line under no-load condition(a) The receiving-end voltage is less than the

sending-end voltage(b) The sending-end voltage is less than the

receiving - end voltage(c) The sending-end voltage is equal to the

receiving - end voltage(d) None of these

23. Ferranti effect on long overhead line is experiencedwhen it is(a) Lightly loaded(b) On full load at unity pf.(c) On full load at 0.8 pf lead(d) None of these

24. The A B C D constants of a 3 phase transposedtransmission line with linear and passive elements(a) Are always equal(b) Never equal(c) A and D are equal(d) B and C are equal

25. The values of A, B, C and D constants for a shorttransmission line are respectively(a) Z, 0, 1 and 1 (b) 0, 1, 1 and Z(c) 1, Z, 0 and 1 (d) 1, 1, Z and 0

26. The angle of A, constant of the transmission linenormally lies between(a) 62°- 70° (b) 90°-70°(c) 40°-10° (d) 10°-0°

27. For a transmission line with resistance R reactanceX and negligible capacitance, the generalisedconstant A is(a) 0 (b) 1(c) R + j X (d) R + X

28. The value of the ‘A’ parameter of a transmissionline(a) Increases with the increase in length of the line(b) Decreases with the increase in line length(c) Is independent of line length(d) None of the above

29. For a medium length transmission line, A is(a) Equal to B(b) Equal to C(c) Equal to D(d) Not equal to any of the above

30. The generalised constant A for a medium line hasmagnitude(a) Close to but less than 1(b) Close to but greater than 1(c) Nearly equal to the series impedance of the line(d) None of the above

31. A 220 kV, 20 km long 3-phase transmission linehas the following A, B, C D constants.A = D = 0.96 3°, B = 55 65° /phase C =0.0005 80° S/phase. Its charging current perphase is

(a)11 A

3 (b) 11 A

(c) 220 A (d)220 A

332. The velocity of propagation of electro-magnetic

waves on overheas lines is(a) 3 × 108 m/s (b) 3 × 108 km/s(c) 3 × 1010 m/s (d) 3 × 108 km/hour

33. A cable has the following characterisicsL = 0.20/H/m and C = 196.2 pF/m.The velocity of wave propagation through the cableis(a) 32 m/s (b) 159.24 m/s(c) 0.0312 m/s (d) 159.24 m/s

34. The square root of the ratio of line impedance andshunt admittance is known as the line(a) Surge impedance (b) Conductance(c) Susceptance (d) Admittance

35. Which of the following statements is correct?(a) Surge impedance is the impedance at the time

of breakdown of voltage(b) Surge impedance and characteristic impedance

for a transmission line are the same(c) Surge impedance is the impedance o

transmission line when corona takes place(d) None of the above

ENGINEERS ACADEMY



EE : Power Systems Modelling of Transmission Line | 6136. The characteristic impedance of a transmission line

depends upon(a) Shape of the conductor(b) Conductivity of the conductor material(c) Geometrical configuration of the conductors(d) None of the above

37. In case the characteristic impedance of atransmission line is equal to the load impedance(a) The system will resonate badly(b) All the energy sent will be absorbed by the load(c) All the energy sent will pass to the earth(d) All the energy will be lost in transmission lineas transmission losses

38. In a transmission line of negligile resistance, thesurge impedance will be

(a) L / C (b) C/L

(c)1LC (d) LC

39. Characteristic impedance of an overheadtransmission line is usually in the range of(a) 100 to 200 (b) 200 to 300 (c) 0 to 100 (d) 400 to 500

40. Surge impedance of a transformer is in the rangeof(a) 80 - 100 (b) 400-500 (c) 1,000-2,000 (d) None of these

41. The surge impedance of a 400 km long over headtransmission line is 400 For a 200 km length ofthe same line, the surge impedance will be(a) 200 (b) 800 (c) 400 (d) 100

42. Surge impedance values for cables are(a) Higher than those of overhead lines(b) Lower than those of overhead lines(c) Of the same order as those of overhead lines(d) None of these

43. Multiple conductor lines have(a) Lower surge impedance than single conductor

lines(b) Higher surge impedance than single line

conductors(c) Higher surge impedance than single conductor

lines for short lengths and lower surgeimpedance for long lines.

(d) None of these44. For a distortionless transmission line

(a) RL = GC (b) RC = GL(c) RG = LC (d) RLGC = 0

45. The propagation constant of a transmission line isgiven as

(a) j LC (b) j LC

(c) j L/C (d) j C/L

46. The transmission capacity of a line at 50 Hz frequencyas compared to that at 60 Hz frequency is(a) Lower (b) Higher(c) The same (d) All of the above

47. When the load on a transmission line is equal to thesurge impedance loading(a) The receiving- end voltage is less than the

sending-end voltage(b) The sending-end voltage is less than the

receiving-end voltage.(c) The receiving-end voltage is equal to the

sending-end voltage(d) None of these

48. The recieving-end voltage of a transmission linewill be greater than the sending voltage if the loadis(a) Greater than SIL (surge impedance loading)(b) Less than SIL(c) Equat to SIL(d) None of these

49. The SIL of a single circuit 220 kV line is around(a) 120 MW (b) 90 MW(c) 120 MW (d) 600 MW




50. A surge voltage of 1,000 kV is applied to anoverhead line with its receiving-end open, If thesurge impedance of the line is 500 , then the totalsurge power in the line is(a) 2,000 MW (b) 500 MW(c) 2 MW (d) 0.5 MW

51. The L/C ratio for 132 kV and 400 kV lines aretypically 160 × 103 and 62.5 × 103 respectively. Thenatural 3-phase loading for the two lines will berespectively(a) 108.9 and 2,560 MW(b) 44 and 2,560 MW(c) 44 and 640 MW(d) 640 and 44 MW

52. The propagation constant of a transmission line is0.15 × 10–3 + j 1.5 × 10–3. The wavelengtha of thetravelling wave is

(a)31.5 10

2

(b) 32

1.5 10

(c)31.5 10

(d) 31.5 10

53. For a good voltage profile under no-load condition,a long line needs(a) Shunt capacitors at receiving end.(b) Shunt reactors at the receiving end(c) Shunt resistance at receiving end(d) None of these

54. No-load compensation of a high voltage line involves(a) Shunt capacitors(b) Shunt reactors(c) Series capacitors(d) None of these

55. Full-load compensation in a line requires(a) Shunt capacitors(b) Series capacitors(c) Transformers(d) shunt reactors

56. Use of additional shunt capacitor can be made forincreasing the capability of line as it(a) Reduce surge impedance Z0

(b) Increase phase shift (c) Increase in (d) All of the above

57. To increase the transmission capability of a highvoltage long line(a) The resistance can be increased(b) The resistance can be decreased(c) The series reactance can be reduced(d) The shunt admittance can be reduced

58. Power dispatch through a line can be increased by(a) Installing series capacitors(b) Installing shunt capacitors(c) Installing series reactor(d) Installing shunt reactor

59. The power transmitted will be maximum when(a) Line reactance is high(b) Corona losses are minimum.(c) Sending-end voltage is more(d) Receiving-end voltage is more

60. The capacity of a transmission line can be increasedby reducing(a) Line inductance(b) Line capacitance(c) Sending-end voltage(d) Any of the above

61. For constant voltage transmission, the voltage dropalong the line is maintained constant by installing(a) Capacitors(b) Inductors(c) Resistors(d) Synchronous phase modifiers at the receiving end

62. Constant voltage transmission have the drawback(s)of(a) Increase of short-circuit current of the system(b) Lower reserve of lines in case of line trouble(c) Increased risk of interruption of supply due to

falling of synchronous motors out ofsynchronous motors out of synchronism

(d) All of the above

ENGINEERS ACADEMY



EE : Power Systems Modelling of Transmission Line | 6363. Constant voltage transmission have the drawback(s)

of(a) Requirement of large x-section conductor for

transmission of same power(b) Increased risk of interruption of supply(c) Reduced power factor at the time of moderate

and heavy loads(d) All of the above

64. Constant voltage transmission have theadvantage(s) of(a) availability of steady voltage at all loads at the

receiving end.(b) Possiblility of better protection for the line due

to possible use of higher terminal reactances(c) Possibility of carrying increased power for a

given conductor size in case of long distanceheavy power transmission.

(d) All of the above65. Constant voltage transmission have the

advantage(s) of(a) Increase of short-circuit current of the system(b) Large reserve of lines in case of line trouble(c) Improvement of power factor at the times of

moderate and heavy loads(d) All of the above

66. A synchronous phase modifier supplies(a) Both active and reactive powers(b) Both lagging and leading reactive power(c) Inductive reactive power only(d) All of the above

67. A synchronous machine has higher capacity for(a) Leading power factor(b) Lagging power factor(c) Unity power factor(d) None of these

68. A synchronous phase modifier as compared tosynchronous motor fo the same rating has(a) Larger shaft diameter and higher speed.(b) larger shaft diameter and higher speed(c) Larger shaft diameter and smaller speed.(d) Smaller shaft diameter and smaller speed.

69. Phase modifier is normally installed in case of(a) Short transmission lines(b) Medium length lines(c) Long lines(d) For any length of lines

70. Which of the following statements is not true?(a) Synchronous phase modifiers are installed at

sending end.(b) Synchronous phase modifiers are installed at

load end.(c) Synchronous phase modifiers are nothing but

synchronous motors (specially designed).(d) Synchronous phase modifiers do not carry load.

71. Over-excited synchronous phase modifier(a) Draws a lagging current.(b) Draws a leading current.(c) Supplies a leading current.(d) Supplies a lagging current.

72. Capacitors are used in power system to(a) Improve supply power factor(b) Improve voltage regulation.(c) change the load supply power factor(d) All of the above

73. Series capacitors on transmission lines are of littleuse when(a) The load VAR requirement is small.(b) The load VAR requirement is large.(c) The load VAR requirement is fluctuating(d) Series capacitiors are never used in

transmission lines74. The reactive power transfer over a line mainly

depends on(a) Power angle (b) |VS| – |VR|(c) VS (d) VR

75. Constant power locus of a transmission line ataparticular sending-end and receiving ena voltage is(a) a straight line (b) a circle(c) a parabola (d) an ellipse




76. Transmission line connects(a) Generating station to a switching station/ step

down transformer station.(b) Step down transformer station to service

transformer banks(c) distribution transformer to consumer premises(d) Service points to consumer premises.

77. 1-phase ac power(a) Is constant(b) Pulsates around an average power at double

the supply frequency.(c) Pulsates around the average value at the supply

frequency.(d) None of these

78. Which of the following is usually not the generatingvoltage?(a) 6.6 kV (b) 9.9 kV(c) 11 kV (d) 13.2 kV

79. The highest transmission voltage in India is(a) 765 kV (b) 400 kV(c) 220 kV (d) 132 kV

80. In a transmission system the feeder supplies power to(a) Transformer substations (step up)(b) Service mains(c) Distributors(d) All of the above

81. The electric power can be transmitted by(a) Overhead system (b) Underground system(c) Either (a) or (b) (d) None of the above

82. In India high voltage transmission is mostly by(a) Overhead system (b) Underground system(c) Both (a) & (b) (d) None of the above

83. Transmission and distribution of electric power byunderground system is superior to overhead systemis respect of(a) Appearance and public safety.(b) Maintenance cost(c) Frequency of faults, power failure and accidents(d) All of the above

84. The main drawback (s) of overhead system overunderground system is(a) Underground system is more flexible thenoverhead system(b) Higher charging current(c) Surge problem(d) High initial cost.

85. For the same voltage drop, increasing the voltageof a distributor n-times(a) reduces the x-section of the conductor by n times(b) Increases the x-section of the conductor by n

times(c) Reduce the x-section of the conductor by n2

times(d) Increases the x-section of the conductor by n2

times86. In a transmission system, the weight of copper used

is proportional to(a) E2 (b) E(c) 1/E2 (d) 1/E

87. The volume of copper required for an actransmission line is inversely proportional to(a) Current (b) Voltage(c) Pf. (d) Both (b) and (c)

88. Transmitting power remaining the same, if thesupply voltage of a dc 2-wire distributor is doubledsaving in copper will be(a) 25% (b) 50%(c) 75% (d) 100%

89. For a given amount of power to be transmitted overa certain distance with fixed power loss, the volumeof copper required is(c) distribution transformer to consumer premises(a) Directly proportional to voltage(b) Inversely proportional to voltage(c) Inversely proportional to the square of voltage

and pf of the load(d) Directly proportional to the square of the voltage

and pf of the load90. The approximate cost ratio of a 220 kV, underground

cable transmission and 220 kV O/H transmissionis(a) 50 (b) 25(c) 13 (d) 5

91. The main reason for using high voltage for longdistance power transmission is(a) Reduction in transmission is(b) Reduction in time of transmission(c) Increase in system reliability.(d) None of the above

ENGINEERS ACADEMY



EE : Power Systems Modelling of Transmission Line | 6592. The most economical voltage for transmitting given

power over a known distance by overheadtransmission lines is about(a) 0.3 kV/km. (b) 0.6 kV/km.(c) 1.5 kV/km. (d) 2.5 kV/km.

93. For transmission of power over a distance of 500 km,the transmission voltage should be in the range of(a) 11-22 kV (b) 33-6 kV.(c) 66-110 kV (d) 132-220 kV

94. 66 kV is suitable for transmission of power over(a) 30 km (b) 60 km(c) 120 km (d) 200 km

95. If 3 MW power is to be transmitted over a distanceof 30 km, the desirable transmission voltage will be(a) 11 kV (b) 33 kV(c) 66 kV (d) 3.3 kV

96. If variable part of annual cost on account of interestand depreciation on the capital out lay is equal tothe annual cost of electrical energy wasted in theconductors., the total annual cost will be minimumand the corresponding size of conductor will be themost economical. This statement is known as(a) Lenz’s law (b) Kelvin’s law(c) Faraday’s low (d) Ohm’s low

97. Which of the curves shown in the fig representsthe relation between capital cost and thetransmission voltage

III III

Transmission Voltage

IV

Cap

ital C

ost

in ru

pees

(a) Curve I (b) Curve II(c) Curve III (d) Curve IV

98. For high voltage transmission lines, conductors aresuspended from towers so as to(a) Increase clearance from ground(b) Reduce clearance from ground(c) Take care of increase in length(d) Reduce wind and snow effects

99. Wooden poles are used as line supports for voltagesupto(a) 11 kV (b) 22 kV(c) 66 kV (d) 400 kV

100. Maximum permissible span with wooden poles is(a) 20 m (b) 30 m(c) 50 m (d) 100 m

101. The wooden poles well impregnated with keroseneoil or any preservative compound have life of(a) 25-30 years (b) 20-25 years(c) 10-15 years (d) 5-10 years

102. In order to protect the wooden poles from the actionof termites etc. It is necessary to treat them with(a) lime water (b) kerosene oil(c) Bleaching powder (d) Sodium hydroxide

103. Steel poles for transmission lines need protectionagainst(a) borer (b) Termites(c) Corrosion (d) All of these

104. Steel poles need galvanizing for longer life.Galvanizing is the process of applying a layer of(a) zinc (b) Paint(c) Varnish (d) Tar coal

105. RCC poles usually have the spans of(a) 250-400 m (b) 80-150 m(c) 50-80 m (d) 25-50 m

106. Which support for overhead transmission line hasthe least life?(a) Wooden poles.(b) Fabricated steel structure(c) RCC poles(d) Steel poles

107. In India for distribution of electric power we usuallyuse(a) Wooden poles (b) Steel poles(c) RCC poles (d) Both (b) and (c)

108. Which of the following poles are bulky poles?(a) Wooden poles (b) Tubular steel poles(c) RCC poles (d) Rail poles

109. For installation of switchgears and powertransformers we usually use(a) L-type structure (b) H-type structure(c) A-type structure (d) V-type structure




110. In transmission lines we usually use cross armsmade of(a) Aluminium (b) Copper(c) Steel (d) RCC

111. The conductors used in high tension overhead linesare(a) Stranded (b) Solid(c) Both (a) and (b) (d) None of the above

112. Conductors used in transmission lines are strandedbecause of(a) Increased tensile strength(b) Ease in handling(c) Cheaper in cost(d) Reduced resistivity.

113. Which type of copper wire is most suitable forpower transmission?(a) Soft drawn (b) Medium drawn(c) Hard drawn (d) None of the above

114. Consider the following materials for line conductors:1. Hard drawn copper2. Cadmium copper3. Aluminium4. Galvanised steelThe correct sequence of the descending order oftheir electrical conductivities is(a) 1, 2, 4, 3 (b) 2, 1, 4, 3(c) 2, 1, 3, 4 (d) 1, 2, 3, 4

115. Which of the following properties has got highervalue for aluminium in comparison to that of copper?(a) Electrical resistivity(b) Melting Point(c) Thermal conductivity(d) Specific gravity

116. In overhead lines, we generally use(a) Copper conductors(b) All aluminium conductors(c) ACSR conductions(d) None of these

117. ACSR conductor implies(a) Aluminium conductor steel reinforced(b) All conductors surface treated and realigned(c) anodized core steel reinforced(d) None of the above

118. The steel core used in ACSR conductors in usuallyof(a) Alloy steel (b) Galvanised steel.(c) Stainless steel (d) High speed steel.

119. ACSR is used in place of copper in overhead linesbecause of(a) Higher current carrying capacity(b) Being lighter in weight(c) economy(d) Higher tensile strength

120. ACSR conductors have(a) All conductors made of aluminium(b) Outer conductor made of aluminium(c) Inner conductors made of aluminium(d) No conductors Made of aluminium

121. ACSR conductors having 70 aluminium conductorsand 6 steel conductors will be specified as(a) 70/6 (b) 6/70(c) 70/76 (d) 6/76

122. “Expanded ACSR” are conductors composed of(a) Larger diameter individual strands for a given

cross-section of the aluminium strands.(b) Larger diameter of the central steel strands for

a given overall diameter of the conductor(c) Larger diameter of the aluminium strands only

for a given overall diameter of conductor.(d) A filter between the inner steel and the outer

aluminium strands to increase the overalldiameter of conductor.

123. The function of steel wire in an ACSR conductoris to(a) Compensate for skin effect(b) Take care of surges(c) Provide additional mechanical strength(d) Reduce inductance

124. In ACSR conductors, the insulation betweenaluminium and steel conductors is(a) Bitumin(b) Varnish(c) Insulin(d) No insulation is required

ENGINEERS ACADEMY



EE : Power Systems Modelling of Transmission Line | 67125. Galvanised steel wire is usually used as

(a) Stay wire(b) Earth wire(c) Structural components(d) All of the above

126. The material used for the manufacture of groundwire is(a) Aluminium (b) Galvanised steel(c) Cast iron (d) Stainless steel

127. Guy wire is employed for(a) Providing protection against surges(b) Providing emergency earth route.(c) Supporting the pole(d) All of the above

128. The material (s) used in overhead transmission lineare(a) Steel-cored aluminium(b) Galvanised steel(c) Cadmium copper(d) All of the above

129. Which of the following material is not used fortransmission and distribution of electrical power?(a) Tungsten (b) Copper(c) Aluminium (d) Cadmium copper

130. The age of a transmission line is least affected owingto(a) Weight of the conductor(b) Current through the conductor(c) Atmospheric temperature(d) Ice deposition on the conductors

131. Increase in temperature in overhead transmissionlines causes(a) Increase in stress and length.(b) Decrease in stress and length(c) Decrease in the stress but increase in length(d) None of the above

132. 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

133. 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(d) None of these

134. In a transmission line, sag depends upon(a) Span length(b) Tension in conductors(c) Weight of the conductor pre unit length(d) All of the above

135. Between two supports, due to sag the conductortakes the form of(a) Semi-circle (b) Catenary(c) Hyperbola (d) None of the above

136. The effect of ice deposition on conductor is toincrease the(a) Weight of the conductor(b) Transmission losses(c) Resistance to flow of current(d) Skin effect

137. Which of the following statements is correct?(a) Ice on conductors increases skin effect(b) Wind pressure reduces corona effect(c) Wind pressure is taken to act at perpendicularto that for ice(d) Ice on conductors reduces sag

138. Wind loading in coastal regions is in the range of(a) 40-50 kg/m2 (b) 150 kg/m2

(c) 96 kg/m2 (d) None of the above139. The maximum tension in a section of overhead

line conductor between two supports of unequalheight occurs at(a) The higher support(b) The lower point(c) The midpoint of the conductor(d) None of the above.

140. Stringing chart is useful(a) For finding the sag in the conductor(b) In the design to tower(c) In the design of insulator string(d) Finding the distance between towers




141. 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

142. The effect of wind pressure is more predominanton(a) Insulators(b) Transmission lines(c) Supporting towers(d) None of the above

143. Galloping in transmission line conductors arises dueto(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

144. The sag of the conductors of a transmission line is2.5 m when the span is 250 m. Now if the height ofsupporting tower is increased by 25%, the sag will(a) Reduce by 25%(b) Increase by 25%(c) reduce by 25.5%(d) Remain unchanged.

tI

IIIIIIV

T

145. In an overhead transmission line with theconductors supported between two supports. Thevariation in tension T with atmospheric temperaturet is represented by(a) Curve I (b) Curve II(c) Curve III (d) Curve IV

146. The minimum clearance of high voltage lines fromground across streets is(a) 3 m (b) 5 m(c) 6 m (d) 8 m

147. Minimum horizontal clearance of a low voltage linefrom residential buildings must be(a) 0.6 m (b) 1.2 m(c) 0.9 m (d) 1.6 m

148. If a 132 kV line passes over residential building,the minimum vertical clearance from the roof ofthe building shall be(a) 4.57 m (b) 5 m(c) 6 m (d) 3 m

149. The minimum clearance between 132 kVtransmission line and ground is about(a) 6.4 m. (b) 3.2 m.(c) 10.5 m. (d) 7.5 m.

150. For a 400 kV line, the spacing between phaseconductors is around is about(a) 6.4 (b) 3.2 m(c) 10.5 m. (d) 7.5 m

151. The horizontal spacing between phase conductorsof a 132 kV transmission line is about(a) 8 m (b) 6 m(c) 4 m (d) 2 m

152. Stranded conductors usually have a central wirearound which there are successive layers of 6, 12,18, 24 wires. For n-layers, the total number ofindividual wires is(a) 3 n (n + 1) (b) 2 n (n + 1)(c) 2 n (n + 1) + 1 (d) 2 n (n + 1) + 1

153. The diameter of each strand is d then the diameterof n-layer stranded conductor will be(a) (2n + 1) d (b) 3 (n + 1) d(c) (2n – 1) d (d) 3 (n – 1) d

154. By increasing the transmission voltage to double ofits original value the same power can be dispatchedkeeping the line loss(a) Equal to original value(b) Half the original value.(c) double the original value(d) One-fourth of original value

ENGINEERS ACADEMY



EE : Power Systems Modelling of Transmission Line | 69

ANSWERS SHEET1. Ans. (b)

2. Ans. (a)

3. Ans. (c)

4. Ans. (c)

5. Ans. (c)

6. Ans. (b)

7. Ans. (a)

8. Ans. (c)

9. Ans. (d)

10. Ans. (d)

11. Ans. (c)

12. Ans. (d)

13. Ans. (b)

14. Ans. (a)

15. Ans. (b)

16. Ans. (d)

17. Ans. (a)

18. Ans. (d)

19. Ans. (d)

20. Ans. (c)

21. Ans. (d)

22. Ans. (b)

23. Ans. (a)

24. Ans. (c)

25. Ans. (c)

26. Ans. (d)

27. Ans. (b)

28. Ans. (a)

29. Ans. (c)

30. Ans. (a)

31. Ans. (a)

32. Ans. (a)

33. Ans. (b)

34. Ans. (a)

35. Ans. (b)

36. Ans. (c)

37. Ans. (b)

38. Ans. (a)

39. Ans. (d)

40. Ans. (c)

41. Ans. (c)

42. Ans. (b)

43. Ans. (a)

44. Ans. (b)

45. Ans. (a)

46. Ans. (b)

47. Ans. (c)

48. Ans. (b)

49. Ans. (a)

50. Ans. (a)

51. Ans. (c)

52. Ans. (b)

53. Ans. (b)

54. Ans. (b)

55. Ans. (a)

56. Ans. (a)

57. Ans. (c)

58. Ans. (a)

59. Ans. (d)

60. Ans. (a)

61. Ans. (d)

62. Ans. (d)

63. Ans. (b)

64. Ans. (d)

65. Ans. (c)

66. Ans. (b)

67. Ans. (a)

68. Ans. (b)

69. Ans. (c)

70. Ans. (a).

71. Ans. (b)

72. Ans. (b)

73. Ans. (a)

74. Ans. (b)

75. Ans. (b)

76. Ans. (a)

77. Ans. (b)

78. Ans. (b)

79. Ans. (a)

80. Ans. (c)

81. Ans. (c)

82. Ans. (a)

83. Ans. (d)

84. Ans. (c)

85. Ans. (a)

86. Ans. (c)

87. Ans. (d)

88. Ans. (b)

89. Ans. (c)

90. Ans. (c)

91. Ans. (a)

92. Ans. (b)

93. Ans. (d)

94. Ans. (b)

95. Ans. (c)

96. Ans. (b)

97. Ans. (a)

98. Ans. (a)

99. Ans. (b)

100. Ans. (c)

101. Ans. (a)

102. Ans. (b)

103. Ans. (c)

104. Ans. (a)

105. Ans. (b)

106. Ans. (a)

107. Ans. (d)

108. Ans. (c)

109. Ans. (b)

110. Ans. (c)

111. Ans. (a)

112. Ans. (b)

113. Ans. (c)

114. Ans. (d)

115. Ans. (a)

116. Ans. (c)

117. Ans. (a)

118. Ans. (b)

119. Ans. (c)

120. Ans. (b)




121. Ans. (a)

122. Ans. (b)

123. Ans. (c)

124. Ans. (d)

125. Ans. (d)

126. Ans. (b)

127. Ans. (c)

128. Ans. (d)

129. Ans. (a)

130. Ans. (b)

131. Ans. (c)

132. Ans. (a)

133. Ans. (b)

134. Ans. (d)

135. Ans. (b)

136. Ans. (a)

137. Ans. (c)

138. Ans. (b)

139. Ans. (a)

140. Ans. (a)

141. Ans. (b)

142. Ans. (c)

143. Ans. (a)

144. Ans. (d)

145. Ans. (a)

146. Ans. (c)

147. Ans. (b)

148. Ans. (a)

149. Ans. (a)

150. Ans. (a)

151. Ans. (b)

152. Ans. (c)

153. Ans. (a)

154. Ans. (d)

ENGINEERS ACADEMY Questions Bank EE... · surge impedance loading (a) The receiving- end voltage is...

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