When the power cable passes through a certain load current, it will generate heat. With the increase of load current, the cable surface temperature will be higher. If not treated in time, the consequences can be imagined. For example, if the core temperature of PVC cable is 70 ° C, its surface temperature will decrease by 5~10 ° C. Therefore, the cable surface temperature is basically safe below 60 ℃. In consideration of power maintenance, the lower the temperature, the better. Next, let's take a look at the causes of heating of power cables in operation.
1. The conductor resistance of the power cable does not meet the requirements, resulting in heating of the cable during operation.
2. Improper type selection of power cable leads to small section of cable conductor and overload operation. After long-term use, the heating and heat dissipation of the cable is unbalanced, causing heating.
3. When installing power cables, the layout is too dense, the ventilation and heat dissipation effect is not good, or the cables are too close to other heat sources, which affects the normal heat dissipation of the cables, and will also cause cable heating during operation.
4. Poor joint manufacturing process and loose crimping lead to excessive contact resistance at the joint, which also leads to heating of power cable.
5. The cable insulation is poor, resulting in low insulation resistance and heating during operation.
The partial sheath of power cable is damaged, and the insulation performance is slowly damaged after water ingress, so that the insulation resistance is gradually reduced, and the heating phenomenon during operation is caused.
After the power supply cable heats up, if the cause is not found out and the fault is eliminated in time, the insulation thermal breakdown will occur if the cable runs continuously. This may cause the cable to trip due to interphase short circuit, which may cause fire in serious cases. So we must pay attention to it.
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