Research on Flashover Breakdowns and Prevention Measures of Synthetic Insulator of overhead Power Transmission Line

Abstract

As an anti-pollution flashoverfacility, synthetic insulator is now widely used in the overhead transmission lines in China. It has good mechanical properties, nice anti-pollution flashover performance, strong electrical erosion resistance and high efficiency advantages in operation. However, the lightning, the bird, icing, filth, foreign body and other unknown reasons of flashover fault will influent the safety of overhead transmission lines. Therefore, it is important to improve the safety operation of the overhead transmission line. Structure of Synthetic Insulator Synthetic insulator shape structure is similar to the suspension insulator, including the end fittings, insulation umbrella bellows, bellows and can heart bar. Also known as composite insulators for organic composite insulator, rubber insulator and porcelain insulator, it is by organic synthetic material to form a composite insulator, mainly mandrel, fittings and umbrella skirt sheath and adhesive layer. Fittings is the mechanical loading of the composite insulator of a transmission member, it and the mandrel assembled together to form a composite insulator of the connector. The structure affects the strength of the mandrel play and the mechanical properties of insulator. Umbrella skirt sheath is synthetic insulator insulating parts. Its role is the composite insulators with high enough resistance to wet flashover and pollution flashover of insulation performance, mandrel protection from atmospheric corrosion. The mandrel is bearing components of composite insulators mechanical load, but also is the main component of internal insulation. Bonding layer part is with the adhesive between the sheath and the plug connections; another part is with potting to complete the connection between the umbrella skirts. The quality of the adhesive is directly related to the level of the internal insulation. Characteristics of Synthetic Insulator Advantages Synthetic insulator core rod consists of epoxy glass fiber thermal mixing extrusion and expansion of its strength is 1.5 times than that of ordinary steel and high strength porcelain 3-4 times than axial tension. It also has a strong vibration absorbing ability.Seismic damping performance is very high. This shows that the synthetic insulator mechanical performance superiority manifests itself only in the core itself. Synthetic insulator has a unique hydrophobic performance, in the rain, the wet umbrella insulator corrugated surface does not form a water film, but a drip-drip, to the surface to form a conductive channel, the pollution flashover voltage is higher, is 3 times than that of the same voltage grade porcelain insulator, suitable for used in overhead transmission line in heavy pollution area. However, after a certain number of years of operation, by the role of long-term ultraviolet and electric field, hydrophobic properties will decline year by year, in a long time of rainy days, the water is not easy to recover. Therefore, the synthetic insulator which operates normally for many years sometimes will get unknown causes flashover.