The reasons for cable aging are usually the following:

1. Environment and temperature. The external environment and heat source of the cable will also cause the cable temperature to be too high, insulation breakdown, and even explosion and fire.

2. External force damage. According to the operation analysis in recent years, especially in Haipudong, where the economy is developing rapidly, a considerable number of cable faults are now caused by mechanical damage.

3. Long-term overload operation. In overload operation, due to the thermal effect of the current, the conductor will heat up when the load current passes through the cable. At the same time, the skin effect of the charge, the eddy current loss of the steel armor, and the loss of the insulating medium will also generate additional heat, which will increase the temperature of the cable.

4. The insulation is damp. This situation is also very common and usually occurs at cable joints in direct burial or in pipes. For example, if the cable joint is not qualified and the joint is made in a humid climate, the joint will enter water or be mixed with water vapor. After a long time, water branches will form under the action of the electric field, which will gradually damage the insulation strength of the cable and cause failure.

5. Chemical corrosion. The cable is buried directly in the area with acid and alkali effect, which often causes the armor, lead or outer sheath of the cable to be corroded. The protective layer has been 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. Chemical: The cable corrosion of the unit is quite serious

6. The cable connector is faulty. The cable joint is the weakest link in the cable line, and the cable joint failure caused by the direct fault of the personnel (poor construction) often occurs. In the process of making cable joints, if there are original nets such as joints that are not crimped tightly, insufficient heating, etc., the insulation of the cable head will be reduced, resulting in accidents.