What are the common causes of cable aging? The most direct cause of cable failure due to aging is insulation degradation and breakdown. While there are many factors contributing to insulation degradation, based on actual operational experience, the following scenarios can be summarized.
Causes of Cable Aging
1. External Damage. Operational analysis in recent years, particularly in the rapidly developing Shanghai Pudong area, shows that a significant number of cable failures are caused by mechanical damage. For example, improper cable installation and laying can easily lead to mechanical damage. Civil construction work on directly buried cables can also easily damage the cables in operation. Sometimes, if the damage is not severe, it can take months or even years for the damaged area to completely breakdown and cause a failure. Severe damage can even lead to a short circuit, directly impacting the safety of both the power plant and the user.
2. Insulation Moisture. This is also common, typically occurring at cable joints in directly buried or conduit installations. For example, poorly manufactured cable joints and joints made in humid climates can allow water or water vapor to enter the joints. Over time, this water dendrites, under the influence of the electric field, gradually weaken the cable's insulation and cause failure.
3. Chemical corrosion. Direct burial of cables in areas subject to acid and alkali exposure often causes corrosion of the cable's armor, lead, or outer sheath. Long-term chemical or electrolytic corrosion can lead to the failure of the protective layer, degrading the insulation and causing cable failure. Corrosion in the cable unit can be quite severe.
4. Long-term overload operation. Overload operation inevitably causes conductor heating due to the thermal effect of current. Furthermore, the skin effect of charge, eddy current losses in the armor, and dielectric losses in the insulation also generate additional heat, raising the cable temperature. During long-term overload operation, excessive temperatures accelerate insulation aging, leading to insulation breakdown. Especially in the hot summer months, the temperature rise often causes insulation breakdown at weak points, leading to a higher incidence of cable failures in the summer.
5. Cable joint failure. Cable joints are the weakest link in a cable line, and joint failures caused by direct human error (e.g., poor construction) are common. If construction workers fail to properly crimp or heat the cable joints properly during fabrication, this can degrade the insulation of the cable ends and lead to accidents.
6. Environment and temperature. The external environment and heat sources surrounding the cable can also cause excessive cable temperatures, insulation breakdown, and even explosions and fires.
How to determine cable aging:
1. Is there current leakage or even a short circuit causing a fire?
2. Hardening and cracking of the insulation.
3. Increased contact resistance and heating of the joints.
The main causes of cable aging are as follows:
1. Long-term overload operation. Overload operation inevitably causes conductor heating due to the thermal effect of the load current. Furthermore, the skin effect of the charge, eddy current losses in the steel armor, and dielectric losses in the insulation generate additional heat, raising the cable temperature.
2. Environment and temperature. The external environment and heat sources surrounding the cable can also cause excessive cable temperatures, insulation breakdown, and even explosions and fires.
3. External damage. Operational analysis in recent years shows that a significant number of cable failures are caused by mechanical damage.
4. Insulation moisture. This typically occurs at cable joints in direct burial or conduit installations. Over time, water dendrites form under the influence of the electric field, gradually damaging the cable's insulation and causing failure.
5. Cable joint failure. Cable joints are the weakest link in a cable line, and failures caused by direct human error (such as poor construction) are common.
6. Chemical corrosion. Direct burial of cables in areas subject to acid and alkali exposure often causes corrosion of the cable's armor, lead, or outer sheath. Long-term chemical or electrolytic corrosion can lead to the failure of the protective layer, degrading the insulation and causing cable failure.
Does aging wires increase power consumption?
Aging wires do increase power consumption. If the outer insulation sheath of an aging line is damaged, it not only increases line loss and power consumption, but can also cause circuit fires. It should be replaced promptly.
Prolonged exposure to high temperatures accelerates aging of wires, and excessively high temperatures can ignite the outer insulation and cause fires. In real life, many people who lack basic circuit knowledge simply twist two wires with wire cutters a few times without tightening them, resulting in minimal contact between the two wires at the joint. According to physics, smaller conductor cross-sectional area equals greater resistance, and heat generation (Q) equals I squared (Rt). Increased resistance leads to increased heat generation.
