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Analysis on the Causes of Cable Aging
2024-09-30
What are the reasons for the aging of the cable? The company helps you to summarize, the insulation is reduced and the breakdown is the cause of the aging of the wire and cable. There are many elements that lead to the reduction of insulation. According to the actual operation experience, the following reasons are summarized:
1) cable aging reasons: external force damage. According to the data analysis in recent years, especially in the rapid economic development of Shanghai, most of the cable failures are caused by mechanical damage. For example, the cable is not constructed in accordance with the normal specifications during the laying and installation process, which is easy to cause mechanical damage; the construction of directly buried cables is also particularly easy to damage the cables in operation. Sometimes if the damage is not serious, it will take several years to cause a complete breakdown of the damaged part to form a fault, and sometimes a short circuit fault may occur if the damage is relatively serious, which directly affects the safety of the electricity unit.
2) cable aging reasons: chemical corrosion. If the cable is buried in a place with acid and alkali action, it is likely to corrode the armor or outer protective layer of the cable. The protective layer is subject to chemical corrosion or electrolytic corrosion for a long time, resulting in failure of the protective layer, reduced insulation, and cable failure.
3) cable aging reasons: insulation damp. This situation is also very easy to occur, usually in the cable joints buried or in the pipe. For example, unqualified cable joints and joints are completed under humid conditions, which will cause water to enter the joint or mix with water vapor. Over time, water branches will be formed under the action of electric field, which will gradually damage the insulation strength of the cable and cause failure.
4) Cause of cable aging: cable joint failure. The most vulnerable link in the cable line is the cable joint, and the cable joint failure caused by the personnel not operating according to the regulations often occurs. In the process of making cable joints, if there are reasons such as insufficient crimping and insufficient heating, the insulation of cable head will be reduced, thus causing accidents.
5) cable aging reasons: long-term overload operation. Overload operation, due to the thermal effect of the current, the load current through the cable will inevitably lead to the conductor heating, while the charge skin effect and steel armor vortex loss, insulation media loss will also generate additional heat, so that the cable temperature increases. Long-term overload operation, too high temperature will accelerate the aging of insulation, insulation breakdown. Especially in the hot summer, the temperature rise of the cable often leads to the breakdown of the weak insulation of the cable, so in the summer, the failure of the cable is particularly much.
6) cable aging reasons: environment and temperature. The environmental factors and heat source of the cable will also cause the cable temperature to be too high, insulation breakdown, and even explosion and fire.
What happens to cable aging?
After aging, the cable will consume more electricity. After aging, if the outer insulation sheath is damaged, it will not only increase the line consumption and power consumption, but also cause a fire situation, which should be replaced in time.
The wire will accelerate aging under high temperature for a long time, and when the temperature is too high, it will ignite the outer insulation skin and cause a fire. In our lives, there are many people who do not understand the common sense of circuits. When connecting two wires to each other, they just use wire cutters to twist two or three turns and do not tighten them, which will cause the contact surface of the two wires at the joint to become smaller. According to the common sense of physics, the smaller the cross-sectional area of the conductor, the greater the resistance, the calorific value Q = I square Rt, and the larger the resistance, the larger the calorific value.
How to determine the wire aging?
1, check whether the current leakage and short circuit fire;
2, the insulation skin has no hardening, crack;
3. Whether the contact resistance becomes larger and the joint heats up.
