Abstract: At present, pollution of insulators in artificial contamination test is done by uniform smearing, but natural pollution, affected by wind, raining, insulator shape, pollution, pollutant particle size and other factors, is a non-uniform accumulation on the insulator surface, and the non-uniform contamination has an effect on the insulator U_50%. Based on a study of the natural pollution characteristics of insulators in multiple regions of a large area, different pollution characteristics of the upper and lower surfaces of different umbrella insulators are obtained, and a non-uniform artificial pollution method is proposed for the upper and lower surfaces of insulators based on the natural contamination characteristics. Non-uniform artificial contamination tests were carried out for the insulators under AC/ DC voltage, and the corresponding pollution flashover curves were obtained. The test results show that the contamination of the insulators by non-uniform pollution method is close to the actual operating conditions of insulators, and the testing results are more accurate and reasonable. It is concluded that the more non-uniform of the contamination on the upper and lower surfaces, the larger the U_50% value is, but the incremental amplitude of U_50% decreases and tends to be saturated. The main conclusions of this paper are of great significance for the optimization of insulator string length and type selection.

Key words: insulator, non-uniform pollution method, artificial contamination test, pollution flashover characteristics, insulation coordination