During the long-term operation of the insulation of low-voltage distribution cabinet, a series of physical changes such as softening or melting of solid medium, volatilization of low molecular compounds and plasticizers, and chemical changes such as oxidation, electrolysis, ionization and generation of new substances will occur, resulting in the gradual deterioration of its electrical, mechanical and other properties, such as increased conductivity and dielectric loss, embrittlement and cracking These phenomena are called insulation aging. Insulation aging of low-voltage distribution cabinet will lead to insulation failure, and power equipment can not continue to operate. Therefore, understanding the aging factors of low-voltage distribution cabinet insulation is the basis to solve the problem. The following is a brief introduction to the low-voltage distribution cabinet insulation aging factors?

There are many reasons for insulation aging of low-voltage distribution cabinet, mainly due to thermal, electrical and mechanical forces, as well as moisture (moisture), oxidation, various rays, microorganisms and other factors. The speed of insulation aging of low voltage distribution cabinet is closely related to insulation structure, material, manufacturing process, operating environment, voltage and load.

1. Thermal aging

The insulation of low voltage distribution cabinet is high in the operation process because of the high ambient temperature or the heating of electrical equipment, which leads to the rise of insulation temperature, which forms the oxidation effect of polymerization chain splitting and so on. Under the action of high temperature, the mechanical strength of the insulation of low voltage distribution cabinet decreases, and the structure is deformed. The material is inelastic due to oxidation and polymerization, or the discharge resistance is reduced.

2. Electrical aging

The insulation of low voltage distribution cabinet will be affected by electric field during operation. Under the action of lightning overvoltage and operation overvoltage, local damage may occur in insulation. After the over-voltage, the damage gradually expanded, leading to complete breakdown. When the external electric field reaches the initial discharge voltage of air gap, partial discharge will occur, which will destroy the insulation structure of low-voltage distribution cabinet and gradually reduce its insulation performance.

3. Mechanical aging

Under the action of mechanical load, self weight, vibration, impact and short circuit current, the insulation of low voltage distribution cabinet will be damaged and the mechanical strength will decrease. In addition, the discharge resistance of the material decreases when there is tensile stress in the material. But the compression stress has little effect on its discharge resistance. Because of the residual tensile stress in the process of manufacture and application, it is very important to influence the aging life of materials.

4. Humidity aging

The relative humidity of environment has an effect on the performance of insulation material of low voltage distribution cabinet to withstand surface discharge. Due to the high relative humidity, the discharge results in a layer of semi-conductive layer on the surface of the material, which causes the discharge to self decay. Therefore, under the condition of surface discharge, the electrical aging life of insulation material of low voltage distribution cabinet increases with the increase of relative humidity within a certain range of relative humidity

5. Chemical aging

The insulation of low voltage distribution cabinet will change the material structure and chemical properties under the action of water, acid, ozone and nitrogen oxides, so as to reduce the electrical and mechanical properties.

6. Other aging factors

The insulation materials of the low voltage distribution cabinet used outdoors are directly exposed to sunlight and will also aging under the action of ultraviolet rays.