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, 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. It will cause the cable to generate heat during operation when cable conductor resistance does not meet the requirements.
2. Improper cable selection, 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 is unbalanced to cause heat generation.
3. When the cable is installed, the arrangement is too dense, it will cause 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 connector is not good, that is to say, the crimping is not tight, causes the contact resistance at the joint is too large, which may cause the cable to generate heat.
5. The insulation performance of insulation between phases of the cable is not good, it not only will cause small resistance for insulation, but also Heat occurs during operation.
6. The partial sheath of the armored cable is damaged. After the water enters, the insulation performance will be destructed slowly, resulting in a gradual decrease in the insulation resistance, which will also cause heating in the cable operation.
After the cable generates heat, if no reason is found and troubleshoot in time, the insulation will be broken after the cable continues to run continuously. It will cause the cable to phase-to-phase short-circuit trip, which may cause a fire.