Effectiveness of methods practiced to clean Biological Growth on MV Porcelain Insulators – A Case Study

Biological growth on insulators is one of the reasons for unwanted insulator flashovers leading to MV network failures. Currently the contaminated insulators are being cleaned manually using a wet cloth as an abrasive or using a high-pressure washer attached to a bucket truck. This study aims to increase our understanding on the effectiveness of those cleaning methods. Holike and Buddhama 33kV feeders were selected for this study based on preliminary studies. First electrical tests were conducted on 20 contaminated insulators selected from these feeders. In parallel, samples of biological growth were removed from the insulators, cultured and identified. Finally, six insulators were cleaned using two commonly used methods and repeated key electrical tests. The study shows that manual cleaning of biologically contaminated insulators using a wet cloth or cotton waste is the best method which yield a 53% improvement in hydrophobicity, 24% improvement in wet flashover voltage and 15 times reduction in wet leakage current measurements.