Which Harm Cables Serve Life?
1) External force damage. According to the operation analysis in recent years, a lot of cable faults are caused by mechanical damage. For example: the cable laying and installation are not standardized, which is easy to cause mechanical damage; the civil construction on the directly buried cable is also easy to damage the cable in operation.
2) The insulation is damp. This kind of situation is also very common, generally occurs in the direct burial or the cable joint in the pipe. For example, if the cable joint is not qualified or made in humid climate, it will cause water or steam to enter the joint and form water branches under the action of electric field, which will gradually damage the insulation strength of the cable and cause failure.
3) Chemical corrosion. When cables are directly buried in the areas with acid and alkali effects, the armour, lead skin or outer protective layer of cables will be corroded, and the protective layer will suffer from chemical corrosion or electrolytic corrosion for a long time, which will cause the failure of protective layer, insulation reduction and cable failure.
4) Long term overload operation. In overload operation, due to the thermal effect of current, when the load current passes through the cable, it will inevitably cause the conductor to heat up. At the same time, the skin effect of charge, eddy current loss of steel armor and insulation medium loss will also generate additional heat, thus increasing the cable temperature. Long term overload operation, too high temperature will accelerate the aging of the insulation, and even the insulation is broken down. Especially in the hot summer, the temperature rise of the cable often causes the cable insulation weak place to be first broken down, so in summer, the cable fault is particularly many.
5) Cable connector failure. The cable joint is the weakest link in the cable line, and the cable joint fault caused by the direct fault of personnel (poor construction) often occurs. In the process of making cable joints, if there is an original network such as the joints are not tightly crimped and the heating is not sufficient, the insulation of the cable head will be reduced, which will lead to accidents.
6) Environment and temperature. The external environment and heat source of the cable will also cause the cable temperature to be too high, insulation breakdown, even explosion and fire.