A review of artificial contamination withstand test methods of high voltage outdoor insulators (original) (raw)
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Among the main causes of outdoor insulation failures is their poor specifications in terms of leakage distances. This happens when the selected criteria are unable to cope with all the stresses imposed by the changes in environmental pollutions. Therefore, it is important for utilities to fully understand the actual pollution characteristics of the service environment in which the insulators are operating. In this paper, the pollution severity and performance of some 13.2 kV ceramic insulators, sampled in different areas of a Canadian aluminum factory, are assessed. The investigations were performed taking into account the influence of air humidity. Various characteristics were investigated to assess the pollution levels of the insulators, such as equivalent salt deposit density (ESDD) and non-soluble deposit density (NSDD), surface resistance, and leakage current characteristics (density, 3rd harmonic amplitude, and phase). It was witnessed that the insulators, collected around the...
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Pollution-induced flashover of outdoor ceramic insulators is one of the critical factors which governs power system reliability. Deposition of the airborne particulates and condensation of vapors on the surface forms layers of pollution which cause degradation in their performance. To mitigate this problem, several techniques such as silicon grease coating, RTV coating, increase in creepage distance, and regular washing of the insulators have been tried with varied success. All these methods are quite expensive and add to the overall cost of power delivery. It is observed that due to the deposition of contaminants on the surface of the ceramic insulators, the field around the insulator becomes highly nonuniform which may lead to flashover. In the present work, a simple and inexpensive method that can increase the pollution withstand capability of the polluted ceramic insulators is proposed. As a part of the proposed method, ceramic specimens were prepared, conduction bands were placed and flashover experiments were conducted with and without conduction bands under clean and polluted conditions. From the test results, it can be concluded that by optimally placing the conduction band on the surface of the ceramic insulators, their pollution withstand capability can be significantly enhanced.