Analysis of cable heating causes and consequences

When the power cable passes through a certain load current, it will certainly generate heat. With the increase of 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) cable, core temperature 70 degrees for the upper limit of consideration, the surface temperature will be low 5 ~ 10 degrees.So the cable surface temperature below 60 degrees is basically safe, from the power maintenance considerations, of course, the lower the temperature is the better.

(1) The conductor resistance of the cable does not meet the requirements, resulting in the cable heating during operation.

(2) Improper cable selection causes the conductor section of the used cable to be too small, resulting in overload in operation. After a long time of use, the imbalance of heating and heat dissipation of the cable will cause heating phenomenon.

(3) The cables are arranged too densely, the ventilation and heat dissipation effect is not good, or the cables are too close to other heat sources, which will affect the normal heat dissipation of the cables and may also cause the heating phenomenon in the operation of the cables.

(4) Due to poor joint manufacturing technology and tight compression, the contact resistance at the joint is too large and the cable will generate heat.

(5) Poor interphase insulation performance of cables, resulting in small insulation resistance and heating phenomenon in operation.

(6) Partial sheathing damage of armored cable will cause slow damage to insulation performance after water inlet, gradually reducing insulation resistance and causing heating phenomenon during cable operation.

After the cable produces heat, if the reason is not found, the fault can be removed in time, the insulation thermal breakdown will occur after the cable continues running with power.This may lead to inter-phase short-circuit tripping, which may seriously cause fire