Transmission and Distribution MCQ PDF

1. Bundled conductors are used to

(a) reduce inductance of the line.
(b) reduce both inductance and capacitance.
(c) reduce corona loss.
(d) reduce corona loss and the line inductance.

2. A 3-phase overhead transmission line has its conductors horizontally spaced with spacing between adjacent conductors equal to ‘d.’ If now the conductors of the line are rearranged to form an equilateral triangle of sides equal to `d’ then

(a) average capacitance and inductance will increase.
(b) average capacitance will decrease and inductance will increase.
(c) average capacitance will increase and inductance will decrease.
(d) surge impedance loading of the line increases. [GATE E.E. 1993]

3. Proximity of a line to the earth surface

(a) does not affect its capacitance to neutral.
(b) increases the capacitance to neutral.
(c) decreases the capacitance to neutral.

4. If the effect of earth is taken into account, then the capacitance of line to ground

(a) decreases.
(b) increases.
(c) remains unaltered.
(d) becomes infinite.

5. For equilateral spacing of conductors of an untransposed 3-phase line, we have

(a) balanced receiving-end voltage and communication interference.
(b) unbalanced receiving-end voltage and no communication interference.
(c) balanced receiving-end voltage and communication interference.
(d) unbalanced receiving-end voltage and communication interference.

6. Transmission lines are transposed to

(a) reduce corona loss.
(b) reduce skin effect.
(c) prevent interference with neighboring telephone lines.
(d) prevent short-circuit between any two lines.

7. Transposition of transmission line is done to

(a) reduce line loss.
(b) reduce skin effect.
(c) balance line voltage drop.
(d) reduce corona.

8. High voltage transmission lines are transposed because then

(a) corona losses can be minimized.
(b) computation of inductance becomes easier.
(c) voltage drop in the lines can be minimized.
(d) phase voltage imbalances can be minimized.

9. The concept of an electrically short, medium and long line is primarily based on the

(a) nominal voltage of the line.
(b) physical length of the line.
(c) wavelength of the line.
(d) power transmitted over the line.

10. Equivalent π model is quite suitable for analyzing the performance of transmission line of

(a) 50 km length.
(b) 150 km length.
(c) 250 km length.
(d) All of the above lengths.

11. Which of the following is neglected while analyzing a short transmission line ?

(a) Shunt admittances.
(b) Power losses.
(c) Series impedance.
(d) None of the above.

12. In modeling the equivalent circuit of a short length overhead transmission line, the line resistance and inductance are only considered because line capacitance to ground is

(a) equal to zero.
(b) finite but very small.
(c) finite but very large.
(d) infinite.

13. As compared to sending-end voltage, the receiving-end voltage of a short line under no-load condition is

(a) higher.
(b) lower
(c) remains the same.

14. Which of the following voltage regulation is considered to be the best ?

(a) 2%
(b) 30%
(c) 70%
(d) 98%

15. The regulation of a line at full load 0.8 pf lagging is 12%. The regulation at full-load 0.8 pf leading can be

(a) 24%
(b) 18%
(c) 12%
(d) 4%

16. If in a short transmission line, resistance and inductive reactance are found to be equal and regulation appears to be zero, then the load will

(a) have unity power factor.
(b) have zero power factor.
(c) be 0.707 leading.
(d) be 0.707 lagging.

17. If X is the inductive reactance/phase and R is the resistance/phase of a short transmission line, what is the power factor angle of the load for maximum voltage regulation?

(a) cos^-1 X/R
(b) tan^-1 X/R
(c) cos^-1 R/X
(d) tan^-1 R/X

18. For a short line if the receiving-end voltage is equal to 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.

19. A single phase transmission line of impedance j0.8 ohm 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.

20. For an ac transmission line of length not exceeding 80 km, it is usual to lump the line capacitance at

(a) the sending end.
(b) the receiving end.
(c) the midpoint.
(d) any convenient point.