Talk about the solution to the problem of power cable heating

Power cables are cables used to transmit and distribute electric energy, and power cables are commonly used in urban underground power grids, power station lead lines, internal power supply of industrial and mining enterprises and underground transmission lines
across rivers and seas.
In power lines, the proportion of cables is gradually increasing
.
Power cable is a cable product used to transmit and distribute high-power power in the backbone line of the power system, including 1-500KV and above various voltage levels, various insulated power cables
.

When passing a certain load current, the power cable will definitely heat up, and as the load current increases, the higher the surface temperature of the cable, and if it is not dealt with in time, the consequences can be
imagined.

For example, polyvinyl chloride (PVC) cables are considered with the core temperature of 70 degrees as the upper limit, and the surface temperature will be 5~10 degrees
lower.
Therefore, the surface temperature of the cable is basically safe below 60 degrees, from the power maintenance consideration, of course, the lower the temperature, the better
.

What are the reasons why power cables heat up during operation? Below, through years of experience summary, Xiaobian analyzes the following six main reasons
for power cable heating in operation.

First, the cable conductor resistance does not meet the requirements, causing the cable to generate heat during operation
.
Second, the cable selection type is improper, resulting in the use of the cable conductor section is too small, overload phenomenon in operation, after a long time of use, the cable heating and heat dissipation imbalance caused by heat phenomenon
.
Third, the cable installation 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
.
Fourth, the joint manufacturing technology is not good, the crimping is not tight, resulting in excessive contact resistance at the joint, which will also cause the cable to generate heat
.
Fifth, the insulation performance of the cable is not good, resulting in small insulation resistance, and heat generation will also occur during operation
.
Sixth, the partial sheath of the armored cable is damaged, and the insulation performance is slowly damaged after entering the water, resulting in a gradual decrease in insulation resistance, which will also cause heat generation during cable operation
.

After the power cable generates heat phenomenon, if the cause is not found and eliminated in time, the insulation thermal breakdown phenomenon
will occur after the cable continues to be powered on continuously.
Cause the cable to have a short circuit tripping phenomenon, which may cause fire
in serious cases.

The following eleven factors should be considered when choosing a power cable:

1.
The rated voltage of the cable should be greater than or equal to the rated voltage of the power supply system at the installation point; 2.
The continuous allowable current of the cable should be equal to or greater than the maximum continuous current of the power supply load; 3.
The core section should meet the stability requirements of the power supply system when it is short-circuited; 4.
Check whether the voltage drop meets the requirements according to the cable length; 5.
The minimum short-circuit current at the end of the line should be able to make the protection device operate
reliably.
6.
High breakdown strength; 7.
Low dielectric loss; 8.
Quite high insulation resistance; 9.
Excellent discharge resistance; 10.
It has certain flexibility and mechanical strength; 11.
Long-term stable insulation performance
.