The Shed Optimization On Silicone Rubber Composite Insulators

The use of silicone rubber composite insulators in China has been more than 20 years. Its excellent anti-pollution flashover performance plays an impotant role in preventing the pollution flashover accident in large-scale power system and improving the reliability of grid. The technical problems about aging, pollution flashover, breakdown in the interface of insulator sheds are urgently needed to solve both for the manufacturers and users. By optimizing the formula of composite insulator sheds , structure and interface bonding properties, we can improve the reliability of transmission lines.This paper focuses on the formula optimization and structure of sheds, nondestructive testing on the adhesive interface between shed and core.The operating experience shows that the insulators with different formulations have different service life. Some insulators which just serviced a year or two have a clear feature of aging. First, three preferred SIR formulations of better mechanical and electrical performance were filtered from nine SIR formulations by orthogonal experiment. Based on four different aging tests including ultraviolet aging, damp-heat aging, salt-fog aging, and wheel aging and two different microscopic analysis method including SEM(Scanning Electron Microscope) and ATR-FTIR(Attenuated Total Reflection-Fourier Transform Infrared), the aging performance and mechanism of silicon rubber with different formulations in different aging conditions are systematically studied. Also, the optimal configuration of silicon rubber formula to improve its life is given.Insulators with different type of shed have different natural pollution deposition performance even in the same operating conditions. Shed optimal simulation studies were carried out by Wind Tunnel Testing and PIV(Particle Image Velocimetry); Visualization research on airflow field of composite insulator at different wind speeds were carried out as well. Based on the comparison of test results and numerical simulation, this paper found out the key parameter of shed which influences the pollution deposition and gave an optimal scheme of shed. In this paper, the method of aerodynamics is used in composite outdoor insulation research for the first time, by this method, pollution deposition performance of insulators with different materials and different shapes in dry conditions can be quickly tested. It is a efficient and reproducible method. This is a new idea of shed optimization for porcelain, glass, composite and station post insulators.At present there is no effective non-destructive testing method detecting the quality of interfacial bonding. This paper illustrated a new ultrasonic nondestructive testing method to test the bonding interface between housing and core in the air. This method is used to evaluate the quality of bonding between housing and core before insulators running, and it plays an important role in composite insulator production process monitoring and accident prevention.