External causes of aging of Jiangmen Bridge
The cable tray is mainly insulated by the outer layer of the cable. If the protection is not good, the external gas will be corroded for a long time, the insulation function will gradually decline, and the aging, embrittlement or falling off will not play an insulating role. The insulation on the outside of the cable is made of plastic and rubber. Sometimes aging is found. What is the reason? Then, this small series of problems of Jiangmen bridge are analyzed.
1. The insulation is affected by tide.
In general, this kind of situation is more common, which usually occurs in directly buried or pipe fabric cable joints. For example, the disqualification of cable joints and joints in humid climate will make the joints enter or mix with water vapor, and form water tree under the action of electric field, which will gradually damage the insulation strength of cables and cause defects. From the beginning.
2。 Corrosion of chemical raw materials.
Cables buried directly in acidic and alkaline areas often lead to the corrosion of cable armour, lead sheath or outer protective layer. The long-term chemical or electrolytic corrosion of the protective layer leads to the failure of the protective layer, the reduction of insulation and the failure of the cable.
3. Long term overload operation.
During overload operation, due to the thermal effect of current, when the load current passes through the cable, the load current will certainly cause the conductor to heat up. At the same time, the skin effect of electric charge, the eddy current loss of steel armor and the loss of insulating medium will first generate additional heat, which makes the cable temperature rise. Too long time and high temperature will accelerate the aging of insulation and even insulation breakdown. Especially in hot summer, the temperature rise of cable often leads to cable insulation breakdown. Therefore, summer cable has many disadvantages.
4。 Cable joint failure.
The cable connector is a weak link in the cable line, and the defects of the cable joint are often caused by the direct shortcomings of personnel (poor construction). In the process of cable joint construction, the construction personnel assume that the joint is not tight, which will lead to cable head insulation reduction, heating failure, which will cause trouble.
5. Environmental factors and temperature elements.
The external environment and heat source of cable bridge and surrounding cables can also lead to high temperature, insulation breakdown and serious explosion.
6。 External force damage.
At present, most of the cable defects are mainly caused by mechanical damage. For example, mechanical damage is briefly caused in equipment and equipment cables, and cables in directly buried cables are briefly damaged. In some cases, the damage to the cable is not serious at the time. It may take months or even years before the damaged parts are completely broken, and the short-circuit defect of cable damage is likely to occur, which directly affects the production and safety of cable tray and power unit.
Source: Jiangmen bridge line pipeline http://www.jmyxt.cn/