Power cable heating reasons, and 11 questions should be paid attention to when select the cables
Power cables through a certain load current, has been higher or exceed the maximum continuous operating temperature of the cable (XLPE insulated cables maximum allowable temperature of 90 ℃), the cable will heat a long time, if you do not find the cause of the problem, the cable Continued continuous operation of the insulation will produce insulation breakdown phenomena, resulting in short circuit between the cable tripping phenomenon, may cause serious fire. Cable heating during operation may be caused by the following reasons:
1.The cable conductor DC resistance does not meet the requirements, resulting in cable running fever.
2.Improper cable selection, resulting in the use of the cable cross-section is too small, running overload, prolonged use, the cable heating and cooling imbalance caused by the phenomenon of fever.
3.When the cable is arranged too densely packed, ventilation and cooling effect is not good, or the cable is too close to other heat sources, affecting the normal cooling of the cable, it may also cause the cable to generate heat in the operation of the phenomenon.
4.Joint manufacturing technology is not good, the pressure is not close, resulting in contact resistance at the junction is too large, can also cause the cable to generate heat phenomenon.
5.The cable insulation performance is not good, resulting in less insulation resistance, the operation will have a fever
6.Local damage sheathing cable, water damage to the insulation performance caused by slow, resulting in a gradual reduction of insulation resistance, can also cause cable running fever.
In order to ensure the safe operation of the cables, the following factors should be considered when selecting the power cables during cable design:
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 cable continuous allowable current should be equal to or greater than the maximum continuous current supply load.
3.The core cross-section to meet the stability of the power supply system short-circuit requirements.
4.Check the voltage drop according to the cable length to meet the requirements.
5.The minimum short circuit current at the end of the circuit should be able to protect the reliable operation of the device.
6.High breakdown strength.
7.Low dielectric loss.
8.A very high insulation resistance.
9.Excellent discharge resistance.
10.With a certain degree of flexibility and mechanical strength.
11.Long-term insulation stability.