1. Long-term overload operation.
In overload operation, due to the thermal effect of the current, the conductor will inevitably heat up when the load passes through the cable. At the same time, the skin effect of the electric charge, the eddy current consumption of the steel armor, and the consumption of the insulating medium will also generate additional heat, which will increase the cable temperature.
In the case of long-term overload operation, the excessive temperature will accelerate the aging of the insulation, and even the insulation will be broken down. More and more in the hot summer, the temperature rise of the cable usually causes the weak part of the cable insulation to be broken down first, so in the summer, the obstacles of the cable are more unique.
2. External force damage.
According to the operation analysis in recent years, a considerable number of cable obstacles are now formed due to mechanical damage. For example, non-standard construction during cable laying and installation will easily cause mechanical damage; civil construction on directly buried cables is also very easy to damage the cables in operation.
Occasional damage does not matter, it will take months or even years for the complete breakdown of the damage site to form a barrier. Occasional damage may cause short-circuit obstacles, which directly affect the safe production of electricity and electricity consumption units.
3. Cable joint obstruction.
The cable joint is the weakest link in the cable line, and the cable joint obstacles caused by poor construction often occur. In the process of manufacturing cable joints, if there are reasons such as insufficient crimping of joints, insufficient heating, etc., the insulation of the cable head will be reduced, thereby causing obstacles to the cable joints.
4. The insulation is damp.
This condition is also very common and usually occurs at cable joints in direct burial or in pipes. For example, the manufacture of cable joints is different and the joints are made under humid climate conditions, which will cause the joints to enter water or mix 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 form obstacles.
5. Chemical attack.
Spiral cables are directly buried in areas with acid and alkali effects, which often cause the armor, lead or outer sheath of the cable to be corroded. The protective layer has been subjected to chemical erosion or electrolytic erosion for a long time, resulting in the failure of the protective layer and the reduction of insulation. form a cable barrier.
Skype: verdecable