Transmission and Distribution line MCQ Part-6

Transmission line Inductance MCQ

1. Consider a long, two-wire line composed of solid round conductors. The radius of both conductors is 0.25 cm and the distance between their centres is 1 m. If this distance is doubled, then the inductance per unit length.

a. Halves

b. Doubles

c. Increases but does not double

d. Decreases but does not halve  

2. 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

3. 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

4. The inductance of a single-phase two-wire line is given by (D is the distance between conductors and r is the radius of conductor)________.

a. 0.4 log_e  (D/r) mH/km

b. 0.55 log_e  (D/r) mH/km

c. 0.4 log_e  (r/D) mH/km

d. 0.55 log_e  (r/D) mH/km

5. For 11 kV line, the inductance per km per phase will be of the order of______.

a. 1 H

b. 0.1 H

c. 0.1 mH

d. 1 mH

6. For a single-phase overhead line having solid copper conductors of diameter 1 cm spaced 60 cm between centres, the inductance in mH/km is____________.

a. 0.05 + 0.2 log 60 

b. 0.2 log 60

c. 0.05 +0.2 log (60/0.5)

d.0.2 log (60/0.5)

7. A 3-phase transmission line has its conductors at the corners of an equilateral triangle with side 3m. The diameter of each conductor is 1.63 cm. The inductance of the line per phase per km is__________.

a. 1.232 mH

b. 1.182 mH

c. 1.093 mH

d. 1.043 mH

8. The conductors of 10 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. 19.6 mH

b. 23.8 mH

c. 45.3 mH

d. 50 mH

9. 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

10. The inductance of a transmission line is minimum when_______.

a. GMD is high

b. GMR is high

c. GMD is low and GMR is high

d. Both GMD and GMR are high

Transmission line conductor MCQ

11. For a given conductor the value of GMR is_________.

a. Larger for capacitance calculation

b. Larger for inductance calculation 

c. Same for both capacitance and inductance calculation

12. Hollow conductors are used in transmission lines to________.

a. Reduce weight of copper

b. Improve stability

c. Reduce corona 

d. Increase power transmission capacity

13. Bundled conductors are employed to improve________.

a. Corona performance of the line

b. Mechanical stability of the line

c. Current carrying capacity of the line

d. Appearance of the transmission line

14. In hv transmission, the spacing between sub-conductors of a bundle is approximately_________.

a. 3.5 cm

b. 20 cm

c. 40 cm

d. 80 cm

15. For a stranded conductor, the ratio of GMR to actual radius is________.

a. Equal to 0.7788

b. Less than 0.7788

c. Equal to 1

d. More than 1

16. 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 

 

17. Bundled conductors in EHV transmission system provide___________.

a. Reduced capacitance 

b. Increased capacitance

c. Increased inductance

d. Increased voltage gradient

18. 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 sag

d. Reduce corona

 

19. 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

 

20. Following effects are associated with transmission lines________.

1. Skin effect        2. Corona effect         3. Proximity effect

The effective resistance of a conductor is increased by 

a. 1 only

b. 1 and 3 only

c. 2 and 3 only

d. 1,2 and 3

 

21. Capacitance in equivalent circuit of a transmission line is due to________.

a. Presence of magnetic flux

b. Leakage of current

c. Current in the line

d. Difference in potential of line

22. 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 decrease and capacitance will increase

d. The inductance will increase and the capacitance will decrease   

23. The charging reactance of 50 km length of the line is 1500 ohm. What is the charging reactance for 100 m length of the line ?

a. 1500 ohm

b. 3000 ohm

c. 750 ohm

d. 600 ohm

24. Proximity of a line to the earth surface________.

a. Increases the capacitance to neutral 

b. Decreases the capacitance to neutral

c. Does not affect its capacitance to neutral

25. If the effect of earth is taken into account, then the capacitance of line to ground_________.

a. Decreases

b. Increases

c. Becomes infinite

d. Remains unchanged

Transmission and distribution line MCQ Part-1

Transmission and Distribution line MCQ Part-2

Transmission and Distribution line MCQ Part-3

Transmission and Distribution line MCQ Part-4

Transmission and Distribution line MCQ Part-5

Transmission and Distribution line MCQ Part-7