Cables Model Quiz practies questions test2

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1. If a cable of homogeneous insulation has a maximum stress of 10 kV/mm, then the dielectric strength of insulation should be _____.
5 kV/mm	10 kV/mm
15 kV/mm	30 kV/mm

2. In the cables, sheaths are used to ______.
prevent the moisture from entering the cable	provide enough strength
provide proper insulation	none of the above

3. The intersheaths in the cables are used to ______.
minimize the stress	avoid the requirement of good insulation
provide proper stress distribution	none of the above

4. The electrostatic stress in underground cables is _______.
same at the conductor and the sheath	minimum at the conductor and maximum at the sheath
maximum at the conductor and minimum at the sheath	zero at the conductor as well as on the sheath

5. The breakdown of insulation of the cable can be avoided economically by the use of _____.
inter-sheaths	insulating materials with different dielectric constants
both (a) and (b)	none of the above

6. The insulation of the cable decreases with _____.
the increase in length of the insulation	the decrease in the length of the insulation
either (a) or (b)	none of the above

7. A cable carrying alternating current has _____.
hysteresis losses only	hysteresis and leakage losses only
hysteresis, leakage and copper losses only	hysteresis, leakage, copper and friction losses

8. In a cable the voltage stress is maximum at ______.
sheath	insulator
surface of the conductor	core of the conductor

9. Capacitance grading of cable implies ______.
use of dielectrics of different permeabilities	grading according to capacitance of cables per km length
cables using single dielectric in different concentrations	capacitance required to be introduced at different lengths to counter the effect of inductance

10. Underground cables are laid at sufficient depth _____.
to minimise temperature stresses	to avoid being unearthed easily due to removal of soil
to minimise the effect of shocks and vibrations due to gassing vehicles, etc.	for all of the above reasons

11. The advantage of cables over overhead transmission lines is ______.
easy maintenance	low cost
can be used in congested areas	can be used in high voltage circuits

12. The thickness of metallic shielding on cables is usually ______.
0.04 mm	0.2 to 0.4 mm
3 to 5 mm	40 to 60 mm

13. Cables for 220 kV lines are invariably _____.
mica insulated	paper insulated
compressed oil or compressed gas insulated	rubber insulated

14. Is a cable is to be designed for use on 1000 kV, which insulation would you prefer ?
Polyvinyle chloride	Vulcanised rubber
Impregnated paper	Compressed SFe gas

15. If a power cable and a communication cable are to run parallel the minimum distance between the two, to avoid interference, should be _____.
2 cm	10 cm
50 cm	400 cm

16. Copper as conductor for cables is used as _____.
annealed	hardened and tempered
hard drawn	alloy with chromium

17.The insulating material should have _____.
low permittivity	high resistivity
high dielectric strength	all of the above

18. The advantage of oil filled cables is _____.
more perfect impregnation	smaller overall size
no ionisation, oxidation and formation of voids	all of the above

19. The disadvantage with paper as insulating material is _____.
it is hygroscopic	it has high capacitance
it is an organic material	none of the above

20. The breakdown voltage of a cable depends on _____.
presence of moisture	working temperature
time of application of the voltage	all of the above