Factories are manufacturing power cables under controlled environment and with great supervision. The cables produced by them include XLPE power cables, industrial power cables, PVC power cables, etc. These cables are tested according to standard testing guidelines prior acceptance for use.
The weakest part of any underground cable system is its joint that has three types of stresses that are predominant. These are thermal stress, electrical stress, and mechanical stress.
Types of failures in power cables
There are many common reasons behind power cable failures. For instance, digging activities of other utilities can damage power cables. Ageing of power cables is another reason behind failure. Power cable manufacturers have reserved three categories for types of failures. These are as under-
- In conductor – Most found in joints
- In Insulation – mostly found in joint or cable. It happens due to ageing.
- In Sheath – It happens in cable
Failure in insulation of accessories and cables are usually happen due to ageing that is caused by-
- Partial discharge
- Thermal Breakdown
- Electrical treeing
- Water treeing
Thermal breakdown
This is a common breakdown in any insulation of the cable. You can recognize a thermal breakdown in two ways. One is when the breakdown channel is radial. Second is typical burning smell from the breakdown area. However, this type of breakdown is rare in XLPE power cables, but if the insulating material properties are inferior then this may happen.
Electrical breakdown
This type of breakdown in polymeric cables can occur because of treeing.
Ageing of power cable
Ageing is used for old PILC cables that are still in use since 50 years. It is a natural process of degradation of insulation. There are many factors behind ageing but the major one is the cyclic overloading. Overloading heats up the paper insulation that lets the impregnation oil to dry up. Drying of impregnating oil can be a reason behind failure. The cable sheath reacts with the chemicals present in the soil and leads to corrosion.
This may cause seepage of moisture into the paper insulation and result in cable dielectric breakdown.
These are some reasons behind the failure of power cables. If you need more details about the reasons behind power cables failure, contact XLPE power cables manufacturers and suppliers. You can ask them anything and get additional information on power cables, such as power cable maintenance, power cable service and more.
