The main reasons for UL electronic ageing are as follows:
1. The environment and temperature.
The external environment and heat source of the cable may cause the cable temperature to be too high, insulation breakdown, or even an explosion.
2. Chemical corrosion.
The cable is directly buried in the acid-base area, which often causes the cable armour, leads or outer sheath to be corroded. The protective layer is chemically corroded or electrolytically corroded for a long time, causing the protective layer to fail and the insulation to be lowered and cable failure.
3. External damage.
From the operation analysis in recent years, quite a number of cable faults are now caused by mechanical damage.
4. The cable connector is faulty.
The cable connector is the weakest link in the cable line, and the cable connector failure caused by the direct failure of the personnel (poor construction) often occurs. During the process of making the cable joints, the construction personnel may cause the cable head insulation to be lowered if there is a joint such as a tight crimping or insufficient heating, which may cause an accident.
5. Long-term overload operation
Overload operation, due to the thermal effect of the current, the load current will cause the conductor to heat when passing through the cable. At the same time, the skin effect of the charge and the eddy current loss of the steel crucible and the loss of the insulating medium will also generate additional heat, thereby increasing the cable temperature. Excessive temperatures during the long-term overload operation accelerate the aging of the insulation and the insulation is broken down. Especially in the hot summer, the temperature rise of the cable often causes the cable insulation to be weakened first, so in the summer, the cable is particularly faulty.
6. Insulation is damp
This type of sign is also common and generally occurs at cable joints in direct buried or drained pipes. For example, if the cable joint is not qualified and the joint is made under humid climatic conditions, the joint will be filled with water or mixed with water vapor. After a long time, the water branch will form under the action of the electric field, and the insulation strength of the cable will become dangerous.