291 / 2022-03-15 07:00:02

Dynamic Alumina Settlement Affecting Mechanical Stress and Reliability of Tri-post Insulator in 1000kV GIL

gas insulated line (GIL),post insulator,Micro-alumina epoxy composite,settlement,mechanical stress

Purpose/Aim

With the gradual expansion of the operating scale of gas-insulated transmission pipeline (GIL), the number of tri-post insulators which play a key role in insulation and mechanical support has been increasing. However, the mechanical properties and insulation properties of insulators decrease and even fracture faults occurred frequently, which seriously affects the stable operation of the system. The materials used for insulators contain 67% micron Al₂O₃, which is easy to cause the filler to settle due to the influence of gravity during pouring. Different parts of insulators have different mechanical and electrical properties due to different contents of inorganic fillers. In order to find out the specific degree of filler settlement, the influence of viscosity, particle size and other factors on the density difference of insulators was studied.

Experimental/Modeling methods

According to the particle settling equation, the relationship between the settling rate of particles with different particle sizes and the solution viscosity was determined. Based on Fick's first diffusion law, the particle diffusion at different times in the insulator casting process is determined. The scaled down insulator was poured, and the density difference measured by slice was used to characterize the settlement of filler.

Results/discussion

The settlement of filler is basically completed in 70 min. The density at the lower leg of insulator is the highest. The density difference between the top of the upper leg and the bottom leg of the insulator is greater than 0.2 g/cm³.

Conclusions

The settlement of insulator filler is mainly influenced by particles with larger particle size, and the larger the particle size, the more serious the settlement degree. The difference of mechanical properties caused by different filler contents will seriously affect the reliability of insulators.