Causes and Consequences of Electrical Power Cables

When a power cable passes a certain load current, it will definitely heat up. As the load current increases, the surface temperature of the cable will be higher. If it is not dealt with in time, the consequences can be imagined. "Cable Treasure Cable Application Technology Research Institute" mentioned: polyvinyl chloride (PVC) cable is considered to have a core wire temperature limit of 70 degrees, and the surface temperature will be 5 to 10 degrees lower. Therefore, the surface temperature of the power cable is basically safe below 60 degrees. From a power maintenance standpoint, of course, the lower the temperature, the better.

1. About power cables

Power cables are cables used to transmit and distribute electrical energy. Power cables are often used in urban underground power grids, power station leads, internal power supply in industrial and mining enterprises, and underwater transmission lines across rivers and seas. In power lines, the proportion of power cables is gradually increasing. Power cables are cable products used to transmit and distribute high-power electrical energy in the main line of the power system, including power cables of various voltage levels from 1 to 500KV and above, and various insulating materials.

II. Causes of heating power cables

1. The conductor resistance of the power cable does not meet the requirements, causing the cable to heat up during operation.

2. Improper selection of the power cable model will cause the conductor cross-section of the cable used to be too small, resulting in overload during operation. After long-term use, the heat generation and heat dissipation of the power cable are unbalanced, resulting in heat generation.

3. During installation, the power cables are arranged too densely, the ventilation and heat dissipation effect is not good, or the cables are too close to other heat sources, which will affect the normal heat dissipation of the cables, and may also cause the cables to generate heat during operation.

4. The joint manufacturing process is not good, and the crimping is not tight, resulting in excessive contact resistance at the joint, which will also cause the power cable to heat up.

5. The insulation performance between the phases of the power cable is not good, resulting in low insulation resistance and heat during operation.

6. Part of the sheath of the armored cable is damaged, and the insulation performance will be slowly destroyed after entering the water, resulting in a gradual decrease in the insulation resistance, and will also cause heat during the operation of the cable.

After the power cable heats up, if the cause is not identified and the fault is eliminated in time, the power cable will continue to be energized and run continuously, resulting in thermal insulation breakdown. Causes short-circuit and tripping of power cables between phases, and may cause fire in severe cases.