The most direct cause of cable aging failure is insulation reduction and so that it breakdown. The sensitivity of the insulation is reduced greatly, according to the actual operating experience, summed up in less than the following situations:
1.External damage. In recent years, the operation of the analysis point of view, now a considerable number of cable failures are due to mechanical damage caused. For example: cable laying installation is not standardized construction, likely to cause mechanical damage.
2.Electrical insulation damp. This is also very common, generally occurs in the direct or buried in the cable connector.
3.Chemical corrosion. Cables are buried directly in the area of acid and alkali, often lead to cable armor, lead skin or outer sheath is corroded, protective layer due to long-term chemical corrosion or electrolytic corrosion, resulting in protective layer failure, insulation reduction, Cable failure.