What are the common causes of cable aging? The direct cause of aging failure of wires and cables is breakdown of insulation due to degradation. There are many factors causing the degradation of conductivity-sensitive insulation.
Based on actual operating experience, it can be summarized as follows:
1) Reasons for cable aging: external force damage. Judging from the operation analysis in recent years, especially in Pudong, a city with rapid economic development, a considerable number of cable failures are now caused by mechanical damage. For example: non-standard construction during cable laying and installation can easily cause mechanical damage; civil construction on directly buried cables can also easily damage running cables. l Sometimes, if the damage is not serious, it will take several months or even years for the damaged part to completely break down and cause a failure. Sometimes, if the damage is serious, a short circuit failure may occur, which directly affects the safe production of electrical equipment and power-consuming units.
2) Cause of cable aging: insulation is affected by moisture. This situation is also very common and usually occurs at cable joints directly buried or in pipes. For example, if the cable joints are not made up to standard and the joints are made in humid climate conditions, water will enter the joints or water vapor will be mixed into the joints. Over time, water branches will form under the action of the electric field, which will gradually damage the insulation strength of the cable and cause failure.
3) Reasons for cable aging: chemical corrosion. Cables buried directly in areas with acid and alkali effects often cause the cable's armor, lead sheet or outer sheath to be corroded. The protective layer suffers from chemical corrosion or electrolytic corrosion for a long time, resulting in the failure of the protective layer and reduced insulation, which can also lead to cable failure. Chemical: The cable corrosion situation in the unit is quite serious
4) Cause of cable aging: long-term overload operation. Overload operation, due to the thermal effect of the current, the load current passing through the cable will inevitably cause the conductor to heat up. At the same time, the skin effect of the charge, the eddy current loss of the steel armor, and the insulation dielectric loss will also generate additional heat, thereby increasing the temperature of the cable. During long-term overload operation, excessive temperature will accelerate the aging of the insulation and even cause breakdown of the insulation. Especially in the hot summer, the temperature rise of the cable often causes the weak points of the cable insulation to be broken down first. Therefore, there are particularly many cable faults in the summer.
5) Cause of cable aging: Cable joint failure. Cable joints are the weakest link in cable lines. Cable joint failures caused by direct personnel negligence (poor construction) often occur. During the process of making cable joints, if the construction workers find that the joints are not tightly crimped or heated insufficiently, the insulation of the cable head will be reduced, thus causing an accident.
6) Reasons for cable aging: environment and temperature. The external environment and heat sources where the cable is located can also cause the cable to be overheated, insulation breakdown, or even explode and catch fire.
How to determine the aging of wires
1. Whether there is current leakage or even short circuit and fire;
2. The insulation skin appears hardened and cracked;
3. The contact resistance increases and the joint heats up.
The main causes of cable aging include the following:
1. Long-term overload operation. Overload operation, due to the thermal effect of the current, the load current passing through the cable will inevitably cause the conductor to heat up. At the same time, the skin effect of the charge, the eddy current loss of the steel armor, and the insulation dielectric loss will also generate additional heat, thereby increasing the temperature of the cable.
2. Environment and temperature. The external environment and heat sources where the cable is located can also cause the cable to be overheated, insulation breakdown, or even explode and catch fire.
3. External force damage. Judging from the operation analysis in recent years, a considerable number of cable failures are caused by mechanical damage.
4. The insulation is damp. Generally occurs at cable joints directly buried or in pipes. Over time, water branches are formed under the action of the electric field, which gradually damages the insulation strength of the cable and causes failure.
5. Cable connector failure. Cable joints are the weakest link in cable lines. Cable joint failures caused by direct personnel negligence (poor construction) often occur.
6. Chemical corrosion. Cables buried directly in areas with acid and alkali effects often cause the cable's armor, lead sheet or outer sheath to be corroded. The protective layer suffers from chemical corrosion or electrolytic corrosion for a long time, resulting in the failure of the protective layer and reduced insulation, which can also lead to cable failure.
Will aging wires increase power consumption?
Aging of wires will increase power consumption. After the wires age, if the outer insulation sheath is damaged, it will not only increase wire consumption and power consumption, but also cause circuit fires. Need to be replaced in time.
Electric wires will age faster if exposed to high temperatures for a long time. When the temperature is too high, they will ignite the outer insulation and cause fires. In real life, many people who do not understand circuit knowledge just use wire cutters to twist two or three turns of two wires without tightening them. This results in a very small contact surface between the two wires at the joint. According to physics knowledge, the smaller the cross-sectional area of a conductor, the greater the resistance, and the heat generation Q=I square Rt. The increase in resistance leads to an increase in heat generation.
