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Key Factors Affecting Cable Lifespan
Background
The production and manufacture of all walks of life are inseparable from electricity, and electricity cannot be separated from the cable, so the service life of the cable directly affects the safety of production. The service life of the cable is determined by the oxidation induction period of the sheath material. Generally, cables are designed to use 20 years, the actual life is much larger than this value.
Cable introduction
A wire that transmits electricity or information from one place to another, made of one or more mutually insulated conductors and an outer insulating protective layer. Definition 2: It is usually a rope-like cable stranded by several or several groups of conductors (at least two in each group). Each group of conductors is insulated from each other, and is often twisted around a center. Has a highly insulating cover. The cable has the characteristics of inner energization and outer insulation.
Factors that reduce cable insulation
The most direct cause of cable aging failure is the breakdown of insulation due to degradation. There are many factors that lead to the reduction of cable insulation. According to the actual operation experience, the following situations are summarized.
external injury
According to the operation analysis in recent years, especially in today's rapid economic development, quite a few cable faults are caused by mechanical damage.
Insulation damp
This is also very common and usually occurs at cable joints in direct burial or in pipes. For example, if the cable joint is not qualified and the joint is made in a humid climate, the joint will enter water or be mixed with water vapor. After a long time, water branches will form under the action of the electric field, which will gradually damage the insulation strength of the cable and cause failure.
chemical corrosion
If the cable is buried directly in the area with acid and alkali effect, the armor, lead or outer sheath of the cable will be corroded. Cable failure. Chemical: The cable corrosion of the unit is quite serious.
long-term overload operation
In overload operation, due to the thermal effect of the current, the conductor will heat up when the load current passes through the cable. At the same time, the skin effect of the electric charge, the eddy current loss of the steel armor, and the loss of the insulating medium will also generate additional heat, which will increase the temperature of the cable. During long-term overload operation, excessive temperature will accelerate the aging of the insulation, and even the insulation will be broken down. Especially in hot summer, the temperature rise of the cable often causes the weak part of the cable insulation to be broken down first, so in summer, there are many cable failures.
Faulty cable connector
The cable joint is the weakest link in the cable line, and the cable joint failure caused by the direct fault of the personnel (poor construction) often occurs. In the process of making cable joints, if there are original nets such as insufficient crimping of joints, insufficient heating, etc., the insulation of the cable head will be reduced, resulting in accidents.
environment and temperature
The external environment and heat source of the cable will also cause the cable temperature to be too high, insulation breakdown, and even explosion and fire.
other factors
Other reasons such as normal aging of the cable body or natural disasters.
