Popularity has very high power, manufacturing from all walks of life cannot leave the electricity, the power is inseparable from the cable, so the service life of the cable will directly affect the safety of production, the service life of the cable is determined by the oxidation induction period of sheath material, use 20 years general cable design, real life is far greater than this value.
What are the factors that lead to reduced cable insulation?
1. External damage
From the operation analysis in recent years, especially in the rapid economic development today, a considerable number of cable faults are caused by mechanical damage.
2. Damp insulation
This is also common, usually at the end of a cable in a buried or drain pipe. For example: cable joints made unqualified and in humid climate conditions to do the joint, will make the joint water or mixed with water vapor, for a long time under the action of the electric field to form water branches, gradually damage the cable insulation strength and cause failure.
3. Chemical corrosion
Cables buried directly in areas with acid and alkali effects will often cause corrosion of the cable armor, lead or outer sheath. Long-term chemical or electrolytic corrosion of the protective layer will lead to failure of the protective layer and reduced insulation, and also lead to cable faults. Change: the cable corrosion situation of unit is quite serious.
4. Long-term over-load operation
In overload operation, due to the thermal effect of current, the conductor will inevitably heat up when the load current passes through the cable. Meanwhile, the skin effect of charge, the eddy current loss of steel armor and the insulation medium loss will also generate additional heat, which will increase the cable temperature. In long-term overload operation, excessive temperature will accelerate the aging of insulation and even the insulation will be broken down. Especially in the hot summer, the temperature rise of the cable often leads to the first breakdown of the cable insulation weakness, so in the summer, the cable faults are particularly frequent.
5. Cable joint failure
The cable joint is the weakest link in the cable line. The fault of the cable joint caused by the personnel’s direct fault (poor construction) often occurs. In the process of making the cable connector, if the original network such as the joint is not pressed tightly and the heating is not sufficient, the insulation of the cable head will be reduced, thus causing an accident.
6. Environment and temperature
The external environment and heat source in which the cable is located will also cause the cable temperature to be too high, the insulation to break down, and even the explosion and fire.
7. Other factors
Normal aging of cable body or other reasons such as natural disasters.