CableReason for aging:

1. External force damage. Based on operational analysis in recent years, especially in Shanghai Pudong where the economy is rapidly developing, a considerable number of cable failures are caused by mechanical damage

2. Insulation is damp. This situation is also very common, usually occurring at cable joints buried directly or in ducts. For example, if the cable joint is not made properly or if the joint is made under humid weather conditions, it will cause water or steam to enter the joint. Over time, under the action of an electric field, water branches will form, gradually damaging the insulation strength of the cable and causing faults

3. Chemical corrosion. Directly burying cables in areas with acidic or alkaline effects often causes corrosion of the cable's armor, lead sheath, or outer protective layer. The protective layer may fail due to long-term chemical or electrolytic corrosion, resulting in reduced insulation and cable failure. Chemical: The corrosion of the unit's cables is quite severe

4. Long term overload operation. Overload operation, due to the thermal effect of current, inevitably causes the conductor to heat up when the load current passes through the cable. At the same time, the skin effect of charges, eddy current loss of steel armor, and insulation medium loss also generate additional heat, thereby increasing the temperature of the cable

5. Cable joint malfunction. Cable joints are the weakest link in cable lines, and cable joint failures often occur due to direct human error (poor construction). During the process of making cable joints, if there are reasons such as loose crimping or insufficient heating, the insulation of the cable head may decrease, leading to accidents

6. Environment and temperature. The external environment and heat sources in which cables are located can also cause high cable temperatures, insulation breakdown, and even explosions and fires