In case of PVC cables the mechanical damage during excavation or by any other means may other means may cause a breaking of conductor or a short circuit between conductors of different phases or a short circuit between the conductor and earth. In case of PILC cables, a puncture of the lead sheath during excavation or by any vibration or by any chemical action of corrosive compounds of soil may cause an ingress of moisture resulting damage to the insulation and consequent short circuits. Defective conductors having uneven size and broken strand of conductors excessive drainage of impregnated oil due to the crack in lead shealth or improper end seals and deterioration of oil compound due to heating caused by dielectric losses or overload or poor heat dissipation or exposure to external heat source can be the causes of damage to the cable.

1. What is called “Barrier joint” of cable ?
2. Interview Question of Underground Cable
3. What are varnished cambric insulated cables ?
4. What do you mean by XLPE cable and what are its advantages over conventional cables ?
5. What do you mean by MIND cable and where is it used ?
6. What do you mean by the term “Sheath losses” ?
7. What is the procedure of reducing the sheath losses in sheaths of the three single core cables in a 3-phase system ?
8. What do you mean by the term “Dielectric losses” ?
9. What do you mean by thermal resistance of a single core cable ?
10. What are the load conditions of an underground cable ?
11. what special cares are to be taken for storage of cable drum ?
12. What are the methods of cable laying ?
13. What is soil thermal resistivity ?
14. What is proximity effect ?
15. What are the procedures to be adopted for determining the types of cable faults ?
16. What precaution should be taken while taken a cable through trenches in the following locations (a) Road crossing, (b) Railway crossing & (c) Crossing of water mains ?
17. What is called “Heat shrinkable joint” of cable?
18. What can be the causes of damage to PVC cables and paper insulated cables?