Author: Noyafa–Noyafa Cable Tester
What will happen to the line aging? Cable fault detection Why does the 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, which generally occurs in cable lines that have been in operation for 15 years or more. Line aging What will happen? Cable fault detection Why does cable fault detection often encounter line aging? At present, the insulation aging of cables mainly occurs in the later stage of operation, which generally occurs in cable lines that have been in operation for 15 years or more, resulting in cable failure rates. Substantial Increase. 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 fault detection Cable insulation operates under the action of electricity and heat for a long time, and its physical properties will change, resulting in a decrease in its dielectric strength or an increase in dielectric loss, which eventually causes insulation breakdown and aging failure. The main reasons for 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 overloaded; 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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