400 Important Transmission and Distribution MCQ Question and Answer | PDF Free Download
1.Hot template curves are plots of
- ATemperature and humidity
- BConductor sag and span lengths
- CConductor weight and sag
- DNone of the above
2.The effect of wind pressure is more predominant on
- AInsulators
- BTransmission lines
- CSupporting towers
- DNone of the above
3.Galloping in transmission line conductors arises due to
- AAsymmetrical layers of ice formation
- BVortex phenomenon in light winds
- CHeavy weight of the line conductors
- DAdoption of horizontal conductor configuration
4.Which of the following is reduced by using stock bridge dampers on power overhead transmission lines?
- ASag
- BConductor vibration
- CLine losses
- DMechanical tension
5.The sag of the conductors of a transmission line is 2.5 m when the span is 250 m. now if the height of supporting tower is increased by 25%, the sag will
- AReduce by 25%
- BIncrease by 25%
- CReduce by 12.5%
- DRemain unchanged
6.The spacing between phase conductors of 400 kV line is around
- A8 m
- B11 m
- C14 m
- D17 m
7.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
- A3 n (n+1)
- B2 n (n+1)
- C3 n (n+1) + 1
- D2 n (n+1) + 1
8.The diameter of each strand is d then the diameter of n-layer stranded conductor will be
- A(2 n + 1) d
- B3 (n + 1) d
- C(2 n ? 1) d
- D3 (n ? 1) d
9.Strain type insulators are used
- AAt dead ends
- BAt intermediate anchor towers
- COn straight runs
- DAny of (a) or (b)
10.Wavy structure of pin insulator increases its
- AMechanical strength
- BPuncture strength
- CFlash-over voltage
- DThermal strength
11.Which type of insulator is used on 132 kV transmission lines ?
- APin type
- BDisc type
- CShackle type
- DPin and Shackle type
12.Whenever the conductors are dead-ended or there is a change in the direction of transmission line, the insulators used are of the
- APin type
- BSuspension type
- CStrain type
- DShackle type
13.The number of discs in a string of insulators for 400 kV ac overhead transmission line lies in the range of
- A32 to 33
- B22 to 23
- C15 to 16
- D9 to 10
14.100 percent string efficiency means
- AOne of the insulators discs shorted
- BZero potential across each disc
- CEqual potential across each insulator disc
- DNone of the above
15.If the frequency of a transmission system is changed from 50 Hz to 100 Hz, the string efficiency
- AWill increase
- BWill decrease
- CRemain unchanged
- DMay increase or decrease depending on the line parameters.
16.The string efficiency of a high-voltage line is around
- A100%
- B80%
- C40%
- D10%
17.In three-unit insulator string, voltage across the lowest unit is 17.5 kV and string efficiency is 84.28%. the total voltage across the string will be equal to
- A8.285 kV
- B44.25 kV
- C88.25 kV
- D442.5 kV
18.Two-insulator discs of identical capacitance value C makes up a string for a 22kV , 50 Hz, single-phase overhead line insulation system. If the pin to earth capacitance is also C, then the string efficiency is
- A50%
- B75%
- C90%
- D86%
19.In a cable the sheath radius is R and conductor radius is r. as r changes from 0.5 R to 0.25 R the maximum voltage gradient in the dielectric
- ADecreases by about 6%
- BIncreases by about 6%
- CIncreases by about 15%
- DDecreases by about 15%
20.The insulators may fail due to
- AFlash over
- BShort-circuits
- CDeposition of dust
- DAny of the above