1. External force damage. Judging from the operation analysis in recent years, especially in Pudong, Shanghai, where the economy is developing rapidly, there are quite a lot of cable faults.
All obstacles are caused by mechanical damage.
2. The insulation is damp. This situation is also very common, and generally occurs at the cable joints in direct burial or piping. For example: cable joint production
Unqualified and making joints under humid climate conditions will cause the joints to enter water or water vapor, and for a long time, water will form under the action of electric field.
Tree branches gradually damage the insulation strength of the cable and cause failure.
3. Chemical corrosion. The cable is buried directly in the acid-base area, which will often cause the cable armor, lead skin or outer sheath to be corroded.
The protective layer suffers from chemical corrosion or electrolytic corrosion for a long time, which causes the protective layer to fail, the insulation is reduced, and the cable fails. Change:
The unit’s cable corrosion is quite serious
4. Long-term overload operation. Overload operation, due to the thermal effect of the current, the conductor will inevitably 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 insulation loss will also generate additional heat, which will increase the temperature of the cable.
5. The cable connector is faulty. Cable joints are the weakest link in the cable line. Electricity caused by direct negligence (poor construction) by personnel
Cable connector failure often occurs. In the process of making cable joints, if the joints are not crimped tightly, heating is insufficient, etc.
Because of this, the insulation of the cable head will be reduced, which may cause an accident.
6. Environment and temperature. The external environment and heat source of the cable can also cause the cable to overheat, insulation breakdown, and even explosion and fire.