1) In which climate does the chances of occurrence of corona is maximum?
a. Dry
b. Hot summer
c. Winter
d. Humid
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2) Corona loss can be reduced by using
1. Solid conductor.
2. Hollow conductor.
3. Bundle conductor.
a. 1 only
b. 1 and 2 only
c. 1, 2 and 3 only
d. 2 and 3 only
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3) What is the effect on corona, if the spacing between the conductors is increased?
a. Corona increases
b. Corona is absent
c. Corona decreases
d. None of these
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4) Why are the hollow conductors used?
a. Reduce the weight of copper
b. Improve stability
c. Reduce corona
d. Increase power transmission capacity
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5) Which of these given statements is wrong in consideration with bundled conductors?
a. Control of voltage gradient
b. Reduction in corona loss
c. Reduction in the radio interference
d. Increase in interference with communication lines
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Answer
Explanation
Related Ques
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ANSWER: Increase in interference with communication lines
Explanation:
No explanation is available for this question!
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6) Why are bundled conductors employed?
a. Appearance of the transmission line is improved
b. Mechanical stability of the line is improved
c. Improves current carrying capacity
d. Improves the corona performance of the line
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7) The effect of dirt on the surface of the conductor is to _____________ irregularity and thereby ________________ the break down voltage.
a. Decreases, reduces
b. Increases, increases
c. Increases, reduces
d. Decreases, increases
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8) Which tests are conducted to locate the fault location in the cables?
a. Murray loop test
b. Varley loop test
c. Both (a) and (b)
d. None of these
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9) Find the spacing between the conductors a 132 kV 3 phase line with 1.956 cm diameter conductors is built so that corona takes place, if the line voltage exceeds 210 kV (rms). With go = 30 kV/cm.
a. 1.213 m.
b. 2.315 m.
c. 3.451 m.
d. 4.256 m.
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10) On what factor does the skin effect depend?
a. Cross section of the conductors
b. Supply frequency
c. Permeability of the conductor
d. All of these
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11) What are the line constants in a transmission line?
a. Resistance and series conductance only
b. Series and shunt conductance
c. Resistance, inductance and capacitance
d. Resistance, inductance, capacitance and shunt conductance
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Answer
Explanation
Related Ques
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ANSWER: Resistance, inductance, capacitance and shunt conductance
Explanation:
No explanation is available for this question!
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12) What is the cause of skin effect?
a. Supply frequency
b. Self inductance of conductor
c. High sensitive material in the centre
d. Both (a) and (b)
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13) The conductor carries more current on the surface in comparison to its core. What is this phenomenon called?
a. Corona
b. Ferranti effect
c. Skin effect
d. Proximity effect
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14) By using which conductor is the skin effect reduced?
a. Bundled conductors
b. Stranded conductors
c. Hollow conductors
d. Solid conductors
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15) In which of the transmission systems is the skin effect observed?
a. Cable carrying dc current
b. DC transmission line only
c. AC transmission line only
d. DC as well as AC transmission lines
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16) Skin effect in a conductor is proportional to
a. (Diameter of conductor)1/2
b. Diameter of conductor
c. (Diameter of conductor)2
d. (Diameter of conductor)4
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17) Skin effect is negligible for what supply frequency and for what diameter?
a. < 50 Hz and < 1 cm
b. < 50 Hz and > 1 cm
c. > 50 Hz and < 1 cm
d. > 50 Hz and > 1 cm
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18) The current distribution may not be uniform in a conductor, which effect is this?
a. Skin effect
b. Proximity effect
c. Ferranti effect
d. None of these
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19) Proximity effect is due to the current flowing in the ___________.
a. Earth
b. Sheath
c. Nearby conductors
d. All of these
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20) Proximity effect
a. Is more in large conductors, high frequency
b. Increases the resistance of the conductor
c. Reduces the self reactance
d. All of these
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21) What is the total resistance in a single phase or 2 – wire dc line?
a. Equal to the resistance of either conductor
b. Double the resistance of either conductor
c. Half of the resistance of either conductor
d. None of these
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22) The inductance of a single phase two wire power transmission line per km gets doubled when
a. Distance between the wires is doubled
b. Distance between the wires increased fourfold
c. Distance between the wires is increased as the square of the original distance
d. Radius of the wire is doubled
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Answer
Explanation
Related Ques
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ANSWER: Distance between the wires is increased as the square of the original distance
Explanation:
No explanation is available for this question!
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23) The inductance of a power transmission line increases with
a. Decrease in line length
b. Increase in diameter of conductor
c. Increasing in spacing between the phase conductors
d. Increase in load current carried by the conductors
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Answer
Explanation
Related Ques
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ANSWER: Increasing in spacing between the phase conductors
Explanation:
No explanation is available for this question!
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24) Inductance of a single phase two parallel wire transmission line having conductor radius r and spacing D between conductors is equal to
a. 2 π * 10-7ln D / r
b. 4 * 10-7ln D / r
c. 4 π * 10-7ln D / r
d. 2 * 10-7ln D / r
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25) For a single phase overhead line having solid copper conductors of diameter 1 cm spaced 90 cm between the centres, the inductance in mH/km is
a. 0.05 + 0.2 ln 90
b. 0.2 ln 90
c. 0.05 + 0.2 ln (90/0.5)
d. 0.2 ln (90/0.5)
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26) The conductor of a 15 km long, single phase two wire line are separated by a distance of 1.5 m. The diameter of each conductor is 1 cm. If the conductors are of copper, the inductance of the circuit is
a. 23.81 mH
b. 35.72 mH
c. 32.81 mH
d. 53.72 mH
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27) 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
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28) A single phase line has two parallel conductors 2 metre apart. The diameter of each conductor is 1.2 cm. What is the loop inductance per km of the line?
a. 2.423 mH
b. 1.234 mH
c. 3.267 mH
d. 8.632 mH
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29) Why is the transmission lines transposed?
a. Reduce corona loss
b. Reduce skin effect
c. Prevent interference with the neighbouring telephone lines
d. Prevent short circuit between any two lines
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Answer
Explanation
Related Ques
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ANSWER: Prevent interference with the neighbouring telephone lines
Explanation:
No explanation is available for this question!
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30) A three phase, 50Hz transmission line consists of three equal conductors of radii ‘r’ placed in a horizontal plane with a spacing of 6m between middle and outer conductor. If the radius of each conductor is 12.5 mm, then inductance per phase per km of the transposed line will be
a. 1.33 mH/km
b. 1.65 mH/km
c. 0.38 mH/km
d. 2.145 mH/km
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31) A three phase transmission line has its conductors at the corners of an equilateral triangle with sides 3m. The diameter of each conductor is 1.63 cm. What is the inductance of the line per phase?
a. 1.232 mH
b. 1.184 mH
c. 2.236 mH
d. 2.68 mH
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32) What will be the inductance of each conductor in a three phase, 3 wire system when they are arranged in a horizontal plane with spacing such that D31= 4m, D12 = D23 = 2m. The conductors are transposed and have a diameter of 2.5 cm.
a. 2.22 mH
b. 1.11 mH
c. 3.33 mH
d. 4.44 mH
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33) What is the inductance per phase per km of a double circuit 3 phase line as shown in the fig. The conductors are transposed and are of radius 0.75 cm each.
a. 0.725 mH
b. 0.835 mH
c. 0.623 mH
d. 0.231 mH
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34) Why is high voltage transmission lines transposed?
a. Corona losses can be minimised
b. Computation of inductance becomes easier
c. Voltage drops in the lines can be minimised
d. Phase voltage imbalances can be minimised
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35) The three phase line consists of three conductors each of diameter 21 mm. The spacing is shown in fig. Find the inductance per phase / km.
a. 8.2 * 10-4 H / km
b. 12.22 * 10-4 H / km
c. 5.6 * 10-4 H / km
d. None of these
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36) When is the transposition of conductors in a transmission line done?
a. When the conductors are not equally spaced
b. When the conductors are spaced equilaterally
c. When a telephone line runs parallel to the power line
d. None of these
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37) Assertion (A): Transposition of conductors in a transmission line is necessary.
Reason (R): Corona losses are reduced by transposition of conductors.
a. Both A and R are true and R is the correct explanation of A
b. Both A and R are true and R is not the explanation of A
c. A is true but R is false
d. A is false but R is true
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38) Assertion (A): the concept of GMD is applicable for the calculation of inductance of transmission lines.
Reason (R): The radius of the conductor of transmission lines, in the expression for inductance is not the self GMD of the conductor.
a. Both A and R are true and R is the correct explanation of A
b. Both A and R are true and R is not the explanation of A
c. A is true but R is false
d. A is false but R is true
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Answer
Explanation
Related Ques
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ANSWER: Both A and R are true and R is not the explanation of A
Explanation:
No explanation is available for this question!
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39) In case of stranded conductors, what is the ratio of the GMR to the actual radius?
a. Equal to 1
b. More than 1
c. Equal to 0.7788
d. Less than 0.7788
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40) Ds is the GMR of each subconductor of a four subconductor bundled conductor and d is the bundle spacing. What is the GMR of the equivalent single conductor?
a. 1.09 √ (Ds * d3)
b. 1.09 √ (Ds3 * d3)
c. 1.09 (√ (Ds 3 * d3))1/4
d. 1.09 (√(Ds * d3))1/4
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