Author: Noyafa–Cable Tester Manufacturer
Question: Why does Shenzhen cable fault detection often encounter line aging? Answer: Why does Shenzhen cable fault detection often encounter line aging? At present, the insulation aging of cables mainly occurs in the later stage of operation. General problem: Shenzhen cable fault Why does the detection often encounter the phenomenon of line aging? Answer: Why does Shenzhen cable fault detection often encounter the phenomenon of line aging? At present, the insulation aging of cables mainly occurs in the later stage of operation, and generally occurs in cable lines that have been in operation for 15 years or more. This leads to a significant increase in the cable failure rate. Insulation aging is mainly divided into dendritic aging, electrothermal aging and insulation material aging. The air gap inside the cable insulating medium is freed under the action of the electric field, which reduces the insulation. When the insulating medium is ionized, chemical substances such as ozone and nitrate drum are generated in the air gap, which corrodes the insulating layer. At the same time, the moisture in the insulation causes the insulating fibers to decompose, causing Dielectric strength decreases.
Overheating will accelerate insulation aging and deterioration. The electrical ionization generated by the air gap inside the cable insulation will cause local overheating, carbonization of the insulating material, and a decrease in the dielectric strength. Cable overload is an important factor for cable overheating.
Cables installed in cable-intensive areas, cable trenches and cable tunnels with poor ventilation, parallel or crossed cable paths and heat pipes without effective insulation measures, etc., will overheat the cables and accelerate the damage of the insulation layer. Cable insulation operates under the action of electricity and heat for a long time, and its physical properties will change, which will lead to the reduction of its insulation strength or the increase of dielectric loss, which will eventually lead to insulation collapse and aging failure. The main causes of insulation aging are: 1. Improper selection of cables, which leads to the long-term operation of the cable under overvoltage; 2. The surrounding of the cable line is close to the heat source, so that the cable part or the entire cable line is heated for a long time and prematurely ages; 3. The cable works in Premature aging in an environment that can have adverse chemical reactions with insulation; 4. When multiple cables are running in parallel, one or several of them are in poor contact, causing other parallel cables to run under overload; 5. When making cable accessories, The cable connection tube is not tightly crimped, which increases the contact resistance and causes overheating.
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