Transmission and Distribution line MCQ Part-3

1. The maximum tension in a section of 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

2. 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

3. 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

4. The effect of wind pressure is more predominant on_________.

a. Insulators

b. Transmission lines

c. Supporting towers

d. None of the above

5. 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

6. Which 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

7. 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__________.

a. Reduce by 25%

b. Increase by 25%

c. Reduce by 12.5%

d. Remain Unchanged

8. For a 400 kV line, the spacing between phase conductor is around________.

a. 8m

b. 11m

c. 14m

d. 17m

9. 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. 3n(n+1)

b. 2n(n+1)

c. 3n(n+1)+1

d. 2n(n+1)+1

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

a. (2n+1)d

b. 3(n+1)d

c. (2n-1)d

d. 3(n-1)d

11. Strain type insulators are used______.

a. At dead ends

b. At intermediate anchor towers

c. on straight runs

d. any of (a) or (b)

12. Wavy structure of pin insulator increases its_____________.

a. Mechanical strength

b. Puncture strength

c. Flash-over voltage

d. Thermal strength

13. Which type of insulator is used on 132 kV transmission lines ?

a. Pin type

b. Disc type

c. Shackle type

d. Pin and Shackle type

14. Whenever the conductor are dead-ended or there is a change in the direction of transmission line, the insulators used are of the________.

a. Pin type

b. Suspension type

c. Strain type

d. Shackle type

15. 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

16. The number of discs in 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

17. 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

18. 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

19. 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

20. 100 percent 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

21. In a suspension type insulator the potential drop is________.

a. Maximum across the lowest disc

b. Maximum across the topmost disc

c. Uniformly distributed over the discs

22. 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. May increase or decrease depending on the line parameters

d. Remain unchanged

23. The string efficiency of a high-voltage line is around________.

a. 100%

b. 80%

c. 40%

d. 10%

24. 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________.

a. 8.285 kV

b. 44.25 kV

c. 88.25 kV

d. 442.5 kV

25. Two-insulator discs of identical capacitance value C makes up a string for a 22 kV, 50 Hz, single-phase overhead line insulation system. If the pin to earth capacitance is also C, then the string efficiency is________.

a. 50%

b. 75%

c. 86%

d. 90%

Transmission and distribution line MCQ Part-1

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Transmission and Distribution line MCQ Part-7