Analysis of Several Causes of Wire Aging

The direct cause of wire aging failure is breakdown caused by insulation degradation. There are many factors that can lead to a decrease in insulation performance. Based on actual usage experience, the following situations of wire aging can be summarized.

Several reasons for wire aging:

(1) Reason for wire aging: external force damage. From the operational analysis in recent years, especially in areas with rapid economic development, mechanical damage has led to a considerable number of cable failures. For example, non-standard structures during cable laying and installation can easily cause mechanical damage; Civil buildings directly buried with cables can also easily damage cables in operation. Sometimes, if the damage is not severe, it may take several months or even years to fully decompose the damaged part and form a fault. Sometimes, if the damage is severe, a short circuit fault may occur, which directly affects safety. Production of electricity users.

(2) Reason for wire aging: The insulation is damp. This situation is also common, usually occurring at cable joints in direct burial or pipelines. For example, unqualified cable joints and joints made under humid weather conditions can cause the joints to enter water or steam, and form water branches under long-term electric field action, gradually damaging the insulation strength of the cable and leading to failure.

(3) The cause of wire aging: chemical corrosion. The cable is directly buried in this area with acid and alkali, which usually leads to corrosion of the cable armor, lead skin, or external protective layer. The protective layer is subjected to chemical or electrolytic corrosion for a long time, which leads to the failure of the protective layer and reduces insulation. Cable failure. Chemical: The cable corrosion of the equipment is very severe.

power cable

(4) Reason for wire aging: long-term overload operation. During overload operation, due to the thermal effect of current, when the load current passes through the cable, the conductor will inevitably generate heat. At the same time, the skin effect of charges, eddy current loss of steel armor, and insulation loss also generate additional heat, which will increase the temperature of the cable. During long-term overload operation, excessive temperature can accelerate the aging of the insulation and even damage it. Especially in hot summers, an increase in cable temperature usually leads to the first damage of weak cable insulation, so there are more cable failures in summer.

(5) Reason for wire aging: power cable connector failure. Cable joints are weak links in cable cables, and cable joint failures often occur due to direct personnel failures (poor structure). During the process of making cable joints, if there is an original mesh cover, such as insufficient crimping of the joint, insufficient heating, etc., it will reduce the insulation of the cable head and cause accidents.

(6) Reasons for wire aging: environment and temperature. The external environment and heat source of wires may also cause cable overheating, insulation breakdown, and even explosion and ignition.