Cable fever analysis
When the power cable passes certain load current, it will heat up. With the increase of load current, the temperature of the cable surface will be higher. If it is not handled in time, the consequences can be imagined. Such as: polyvinyl chloride (PVC) cable is based on the core temperature of 70 degrees as the upper limit, the surface temperature will be 5 to 10 degrees lower. Therefore, the cable surface temperature below 60 degrees is basically safe. From the consideration of power supply maintenance, the lower the temperature, the better.
The cause of the cable heating during operation is as follows:
1. Cable conductor resistance does not meet the requirements, causing the cable to generate heat during operation.
2. Improper selection of cables causes the cross-section of the cable used to be too small, causing overload during operation. After a long time of use, the heating of the cable and unbalanced heat dissipation cause heating.
3, the cable is too densely arranged during installation, the ventilation and heat dissipation effect is not good, or the cable is 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, joints manufacturing technology is not good, crimping is not close, resulting in contact resistance at the joint is too large, it will cause the cable to generate heat.
5. The insulation performance between the cables is not good, resulting in a small insulation resistance and heating during operation.
6. The partial sheath of the armored cable is damaged. After the water enters, the insulation performance will cause a slow destruction. As a result, the insulation resistance will be gradually reduced, and the cable will also cause heating during operation.
After the cable generates heat, if the cause is not found and the fault is eliminated in time, the cable will continue to heat up and run, causing thermal insulation breakdown. The occurrence of phase-to-phase short circuit tripping of the cable may cause serious fire hazards.
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