Talking about the causes and consequences of power cable heating


Technical Information



When the power cable passes a certain load current, it will definitely heat up. As the load current increases, the temperature of the cable surface will be higher. If it is not processed in time, the consequences can be imagined. For example, a polyvinyl chloride (PVC) cable is considered to have a core temperature of 70 degrees as the upper limit, and the surface temperature is 5 to 10 degrees lower. Therefore, the cable surface temperature is basically safe below 60 degrees. From the viewpoint of power supply maintenance, of course, the lower the temperature, the better.

The reasons for the heating of the cable during operation are as follows:

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

2. The cable selection type is improper, causing the conductor cross section of the cable to be used to be too small, and an overload phenomenon occurs during operation. After a long time of use, the heat generation and heat dissipation of the cable are unbalanced to cause heat generation.

3. When the cable is installed, the arrangement is too dense, the ventilation and heat dissipation effect is not good, or the cable is too close to other heat sources, which affects the normal heat dissipation of the cable, and may also cause the cable to generate heat during operation.

4. The joint manufacturing technology is not good, the crimping is not tight, and the contact resistance at the joint is too large, which may cause the cable to generate heat.

5, the cable phase insulation performance is not good, resulting in less insulation resistance, heating will also occur during operation.

6. The partial sheath of the armored cable is damaged. After the water enters, the insulation performance will be slowly destructive, resulting in a gradual decrease in the insulation resistance, which will also cause heating in the cable operation.

After the cable is heated, if the fault is not found, the insulation will break down after continuous continuous energization. Causes the cable to phase-to-phase short-circuit trip, which may cause a fire.