When the power cable passes through a certain load current, it will definitely heat up. With the increase of the load current, the surface temperature of the cable will be higher. If it is not handled in time, the consequences can be imagined. Such as: polyvinyl chloride (PVC)
The cable is considered to have a core temperature of 70 degrees as the upper limit, and the surface temperature will be 5 ~ 10 degrees.
So the cable surface temperature below 60 degrees is basically safe, from the power supply maintenance considerations, of course, the lower the temperature, the better.
The reasons for the heating of the power 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. Improper selection of cable type will cause the conductor cross section of the used cable to be too small, resulting in overload during operation. After long-term use, the heat generation and heat dissipation imbalance of the cable will cause the heat generation.
3. When the cables are 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 pressure is not close, resulting in the joint contact resistance is too large, will also cause the cable to produce heating phenomenon.
5, cable phase insulation performance is not good, resulting in insulation resistance is small, the operation will also produce heating phenomenon.
6. The partial sheath of armored cable is damaged, which will cause slow damage to the insulation performance after water inflow, causing the insulation resistance to gradually decrease, and will also cause heat generation during cable operation.
After the power cable generates heating phenomenon, if the cause is not found and the fault is eliminated in time, the insulation thermal breakdown phenomenon will occur after the cable continues to operate continuously.
Cause the cable to have phase-to-phase short circuit trip, which may seriously cause fire.