Underground Cables Interview Questions:
Following are the below Underground Cables Interview Questions and Important Questions which is very useful for interviews and exams
1. Describe general construction of the cable. What are the necessary requirements of a cable ?
2. Discuss the qualities the dielectrics used for cable insulation must have. Also name three dielectrics with their properties used in the manufacture of underground cables.
3. Explain various insulating materials used for cables.
4. What should be the desirable characteristics of insulating materials used in cables ? Discuss the classification of cables according to voltage levels.
5. State the classification of cables (according to voltage) and discuss their general construction.
6. Discuss in brief about the types of cables.
7. What are types of hv and lv cables ? Explain.
8. Explain the construction of H-type cable. What are limitations of solid type cables ?
9. Mention criterion of the cable classification alongwith justification. Draw the extra high tension cable schematic diagram and explain the various terminology.
10. Describe with a neat sketch the construction of a 3-core belted type cable. Discuss the limitations of such a cable.
11. Explain different types of insulating materials for cables. Explain oil-filled cables.
12. Derive an expression for the insulation resistance of a single-core metal sheathed cable.
13. Show that insulation resistance of a cable is inversely proportional to its length.
14. Find expression for the capacitance of a cable per km length.
15. Derive a formula for the electric stress in a single core cable. Where is maximum stress ? Where is it minimum ?
16. Show that the most economical size of conductor in a single core cable is obtained when radius of cable sheath (R) equals er where e is the base of natural log and r is the radius of conductor. Explain dielectric loss and heating of a cable.
17. Derive relation between conductor radius ‘r’ and inner radius of sheath R for stable and satisfactory working of a cable. Discuss the effect of r/R on the stability of the cable.
18. What is meant by grading of cables ? Explain why and how the grading of cable is done.
19. Explain capacitance grading method used in cables.
20. What is meant by capacitance grading of a cable ? Derive expressions for capacitance of and maximum potential gradients in two dielectrics of a graded cable in terms of dielectric constants and radius of core and overall radius.
21. Why is capacitance grading required in cables ? How is it done ?
22. With appropriate derivations compare the performance of cables using (i) capacitance grading (ii) intersheath grading.
23. Explain intersheath grading method used in cables.
24. Explain, how you can find the capacitance of a three core cable.
25. Describe an experiment to determine the capacitance of a belted cable.
26. What are the various methods of laying underground cables ? Explain.
27. Explain direct laying method of laying of underground cables.
28. Explain the dielectric power factor.
29. Derive the expression for the thermal resistance of a single-core cable and a 3-core cable.
30. Write short notes on the following :
- General construction of underground cable.
- Classification of underground cables.
- PILCDSTA cable.
- Oil-filled cables.
- Gas pressure filled cables.
- Grading of cables.
- Laying of underground cables.
- TThermal rating of cables.