1.Aging causes of wires and cables: external damage.According to the operation analysis in recent years, quite a lot of cable faults are caused by mechanical damage.For example: wire and cable installation is not standard construction, easy to cause mechanical damage;It is also easy to damage wires and cables in operation during civil construction on directly buried wires and cables.Sometimes, if the damage is not serious, it will take several months or even years to cause the damaged part to break down completely and form a fault. Sometimes, the damage is serious and short-circuit fault may occur, directly affecting the safe production of the power unit.
2.Aging causes of wires and cables: damp insulation.It is also very common and occurs at the ends of wires and cables that are buried directly or in the drain.For example: cable joints made unqualified and in humid climate conditions to do the joint, will make the joint water or mixed with water vapor, for a long time under the action of the electric field to form water branches, gradually damage the insulation strength of the cable caused by fault.
3. Aging causes of wires and cables: chemical corrosion.If the cables are buried directly in the area with acid and alkali effect, the armored, lead or outer protective layer of the cables will often be corroded. The protective layer will suffer chemical corrosion or electrolytic corrosion for a long time, resulting in the failure of the protective layer and the reduction of insulation, which will also lead to the failure of the wires and cables.The corrosion of cables in chemical units is quite serious.
4.Aging causes of wire and cable: long-term over-load operation.In overload operation, due to the thermal effect of the current, the conductor will inevitably heat up when the load current passes through the cable. Meanwhile, the skin effect of the charge, the eddy current loss of steel armor and the insulation medium loss will also produce additional heat, which will increase the temperature of the wire and cable.In long-term overload operation, excessive temperature will accelerate the aging of insulation and even the insulation will be broken down.Especially in the hot summer, the temperature rise of the cable often leads to the first breakdown of the cable insulation weakness, so in the summer, the cable faults are particularly frequent.
5.Aging causes of wire and cable: cable joint failure.The cable joint is the weakest link in the cable line. The fault of the cable joint caused by the personnel’s direct fault (poor construction) often occurs.In the process of making the wire and cable connector, if the connector is not pressed tightly and the heating is not sufficient, the original network will lead to the decrease of the insulation of the cable head, thus causing an accident.
6. Aging causes of wires and cables: environment and temperature.The external environment and heat source in which the cable is located will also cause the cable temperature to be too high, the insulation to break down, and even the explosion and fire.
Post time: Dec-05-2020