The most direct cause of cable aging failures is breakdown due to reduced insulation. There are many factors that lead to the reduction of sensitive insulation. According to the actual operation experience, it can be summed up in the following situations.
1.External force damage: quite a lot of cable failures are caused by mechanical damage. For example: cable laying and installation are not standardized construction, which is easy to cause mechanical damage; civil construction on direct buried cables is also very easy to damage the cables in operation. Sometimes if the damage is not serious, it will take months or even years to completely break down the damaged part to form a fault, and sometimes a short circuit fault may occur if the damage is serious.
2.Wet insulation: This situation is also very common, and generally occurs at the cable joints in direct burial or in pipes. For example, unqualified cable joints and joints made under humid climate conditions will cause water or water vapor to enter the joints, forming water branches under the action of an electric field for a long time, gradually damaging the insulation strength of the cable and causing failures.
3.Chemical corrosion: The cable is directly buried in an area with acid and alkali effects, which often causes the armor, lead skin or outer sheath of the cable to be corroded. The protective layer is subjected to chemical corrosion or electrolytic corrosion for a long time, resulting in the failure of the protective layer and the reduction of insulation, which will also lead to cable failure.
4.Long-term overload operation: Overload operation, due to the thermal effect of the current, when the load current passes through the cable, it will inevitably cause the conductor to heat up. At the same time, the skin effect of the charge, the eddy current loss of the steel armor, and the loss of the insulation medium will also generate additional heat, which will increase the temperature of the cable. During long-term overload operation, the high temperature will accelerate the aging of the insulation, so that the insulation will be broken down. Especially in the hot summer, the temperature rise of the cable often causes the weak cable insulation to be broken down first, so in summer, there are especially many cable faults.
5.Faulty cable connector: The cable joint is the weakest link in the cable line, and the failure of the cable joint caused by the direct fault of personnel (poor construction) often occurs. In the process of making cable joints, if there are original wires such as joints that are not tightly crimped or insufficiently heated, the insulation of the cable head will be reduced, which will cause accidents.
6.Environment and temperature: The external environment and heat source where the cable is located will also cause the cable temperature to be too high, insulation breakdown, and even explosion and fire.
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Post time: Jul-24-2023
