External insulation of insulator surface has a great relationship with atmospheric contamination. According to the contamination composition and the severity of contamination in the atmosphere, it is divided into four contamination grades, and its creeping distance is specified in detail.
Contaminants are the main factor affecting the external insulation level of insulators. Pollution flashover accidents in power grid are mostly caused by the decrease of insulating level of insulators. The main factors causing the decrease of insulating level are the contamination of insulator surface and the deliquescence of contaminants on insulator surface. Because insulators have been exposed in polluted atmosphere for a long time, the surface of insulators gradually accumulates contamination. These contaminants containing salt, acid and alkaline are generally soluble in water. The contamination dissolves in water and becomes an electrolyte. Their strong conductivity increases the leakage current, which greatly reduces the flashover voltage of insulators and causes flashover of insulators. Therefore, insulator cleaner
on time is necessary.
Contaminants are the main factor affecting the external insulation of insulators and the main object of insulator cleaner, while meteorological conditions play a leading role in influencing the flashover trip of polluted insulators. Dry contamination resistance is very high. Experiments show that it does not reduce the dry flashover voltage of insulators. Once the polluted porcelain surface is wet, the flashover voltage of insulators will be reduced by more than 50%. From the relevant data, it can be seen that fog, dew, drizzle and snow melting are the most dangerous meteorological conditions, and the proportion of polluted flashover tripping is the largest.
Live insulator cleaner is the most effective measure to prevent contaminants. Contaminants affect the external insulation of insulators. Contaminants on the surface of insulators should be removed regularly to ensure that the surface of insulators is clean and improve the insulation level.