When the wires and cables are energized, the metal core will heat up. With the increase of the energization time, the surface temperature of the wires and cables will get higher and higher. If it is not handled in time, the consequences can be imagined. The sheath of our commonly used PVC wires and cables is PVC, which is considered with the core temperature of 70 degrees as the upper limit, and the surface temperature will be 5 ~ 10 degrees lower. Therefore, it is basically safe for the cable surface temperature to be below 60 degrees. From the perspective of power maintenance, the lower the temperature, the better. It is normal for wires and cables to heat up, but there are some cases that can cause wires and cables to overheat. Let's talk about the causes of overheating in use.
1、 The wires and cables are not tightly crimped at the joints, resulting in excessive resistance at the joints, which may overheat the wires and cables when energized for a long time.
2、 In the design, planning and installation of wires and cables, it is not considered thoroughly, and wires and cables that do not conform to the resistance of cable conductors are selected. When the energizing current is greater than the large negative current, overheating will occur.
3、 Improper cable selection results in the conductor cross-section of the cable being used being too small, resulting in overload during transportation. After long-term use, the heating and heat dissipation of the cable are unbalanced, resulting in overheating.
4、 Due to the unprofessional installation personnel, the cables are arranged too densely during installation, 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 may cause overheating of the cables during operation.
5、 The insulation performance between phases of the cable is not good, resulting in low insulation resistance and overheating during transportation.
6、 The local sheath of armored cable is damaged, which will slowly damage the insulation performance after water inflow, resulting in the gradual reduction of insulation resistance and overheating of the cable during operation.
7、 Many inferior wires and cables on the market have poor insulation, resulting in small insulation resistance and overheating after long-term operation.
8、 Improper selection of wire and cable models, such as fire-resistant wires and cables in high temperature or flammable environment.
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