Abstract
The flashover performance of contaminated insulators highly depends on the type of pollutant and its present concentration. In this paper, important agricultural salts (NaCl, K2SO4, NaHCO3, CaSO4, KHCO3, MgSO4, NH4), 2Fe(SO4)2, and 6H2O (ferrous ammonium sulphate, dust, and urea) at different concentrations, and biological contaminants, such as algae and fungi, were taken as pollutants, and the AC flashover behavior of a porcelain-cap-and-pin-type insulator polluted with these two different pollutants was investigated. The experiment was carried out by a semi-natural method, wherein the insulator was first polluted artificially; thereafter, natural fog was applied to measure the wet flashover voltage. Test results indicated that the flashover voltages were affected by both soluble salts and non-soluble components deposited on the insulator surface. In the case of the thickly contaminated layers, non-soluble deposits greatly reduced the flashover voltage. Moreover, by using regression analysis, four empirical models based on different variables were developed. The empirical models developed in the present work represented a good degree of relation in predicting the flashover voltage of naturally contaminated insulators.
Highlights
Outdoor insulator surfaces are covered by environmental pollutants due to natural or industrial sources, or even both
The results showed a low p-value, which indicated that the model still had a quite significant relationship between Flashover voltage (FOV) and equivalent salt deposit density (ESDD)
It is observed that the agricultural contaminants, comprising dust, soluble chemical salts, and inert particles, can reduce the flashover voltage of the insulators up to 16% for the given case when ESDD yield is in the range of
Summary
Outdoor insulator surfaces are covered by environmental pollutants due to natural (deposition of salts in coastal areas by condensation, growing of contaminants, such as algae or fungi, in humid areas) or industrial sources, or even both. Due to the different chemical nature of the pollutants deposited on an insulator surface, the dielectric strength of the insulator is degraded, and sometimes it falls below the flashover withstand value; insulator flashover may happen at operating voltages only [4,5]. The occurrence of flashover due to pollution has become a severe problem in transmission lines and may cause subsequent line outages and total blackouts, leading to catastrophe in a region. The phenomenon of pollution-induced flashover has been studied over the last hundred years, still, the behavior of insulators under pollution is not completely understood
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