Power Systems Questions and Answers – Underground Cables – 1

This set of Power Systems Multiple Choice Questions & Answers (MCQs) focuses on “Underground Cables – 1”.

1. Single core cables for AC systems are not provided with armouring.
a) True
b) False
View Answer

2. Single core cables for ac systems are provided with armouring.
a) True
b) False
View Answer

3. Potential gradient of single core cable is ________________

View Answer

Answer: a
Explanation: The electric field intensity,

4. For a transmission system of voltage ‘V’ volts having the core radius of ‘r’ m and outer radius of ‘R’ m. The maximum dielectric stress on single core cable is ___________

View Answer

5. For a transmission system of voltage ‘V’ volts having the core radius of ‘r’ m and outer radius of ‘R’ m. The minimum dielectric stress on single core cable is ______________

View Answer

6. For a transmission system of voltage ‘765 kV’ volts having the core radius of ‘5’ cm and outer radius of ‘0.40’ m. The maximum dielectric stress on single core cable is _________
a) 7357.7 kV
b) 919.7 kV
c) 4247 kV
d) 530 kV
View Answer

Answer: a
Explanation: The maximum stress will occur at the surface of the conductor such that x(min) = radius of core.

7. The ratio of dielectric stress of the on the cable corresponding to the maximum and minimum is ____________
a) R/r
b) r/R
c) rR
d) (R/r)²
View Answer

Answer: a

8. The condition at which the minimized dielectric stress condition (R/r) will take place is ______________
a) 2.7188
b) 0.7188
c) 1/2.7188
d) 2.7188²
View Answer

Answer: a

9. Grading of the cables is performed in order to achieve ____________
(i) uniform stress
(ii) reduction in quantity of insulation
(iii) reduction in quality of insulation
a) (i), (ii)
b) (ii)
c) (i),(iii)
d) (ii), (iii)
View Answer

10. The resistance of the insulation used for the cables is 40 ohms for a length of ‘x’ km. If the proposed plan needs to extend the transmission line cable to extra ‘2x’ m then the resistance of the cable offered will be _____________ (in ohms).
a) 13.33
b) 20
c) 120
d) 40
View Answer

11. Consider a system having a cable of capacitance 5 nF, with 765 kV star connected at 50 Hz having a power loss in the cable as 82.1 kW. Then the dielectric loss angle is _________(in degrees).
a) 15
b) 7.5
c) 20
d) 4.9
View Answer

Answer: a
Explanation: Dielectric loss = ωCV² tanδ

12. Dielectric power loss of a transmission line cable operating for ‘V’ volts, ‘f’ Hz having a capacitance of ‘C’ Farads with the tangent loss angle of δis ____________
a) ωCV² tanδ
b) ωCV²/tanδ
c) (tanδ/ωCV)²
d) ωCV² tanδ²
View Answer

13. The power losses occurring in the transmission cable has the relation with loss tangent angle as _____
a)
b)
c)
d)
View Answer

14. In a transmission tower having ‘n’ insulators with equivalent pin-to-earth capacitance of ‘C’ farads. For the static shielding of the conductors, the capacitance from the shield to the kth link from the top is ______

View Answer

Sanfoundry Global Education & Learning Series – Power Systems.

To practice all areas of Power Systems, here is complete set of 1000+ Multiple Choice Questions and Answers.

If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]