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Studies on metallurgical contamination accumulation characteristics on ceramic insulator of 500 kV AC transmission line

The composition of metallurgical contamination is rather special, which has a great influence on the contamination accumulation and flashover characteristics of the insulators. In this study, the 500 kV AC line insulators in metallurgical industry area of central China were sampled. The ion composition, element composition, micromorphology and particle size distribution of contamination at high and low end of insulator string were tested, respectively. The equivalent salt deposit density (ESDD) and non-soluble deposit density (NSDD) of high-voltage end, low-voltage end and middle segment of three-phase insulator strings were tested. The results indicate that the contamination particles are irregular in shape and dispersed with each other. The contamination particle size of high-voltage end is larger than that of low-voltage end. The main components of the contamination are Fe2O3 and CaSO4. The ESDD and NSDD of upper surface of upper phase is lower than that of middle phase and lower phase with the cleaning of rainwater. Due to the subsidence of metallurgical contamination from high altitude, the ESDD and NSDD of lower surface of the upper phase is higher than that of middle phase and lower phase. The ESDD and NSDD of lower surface of three phases reduce with the decrease of height.