Pattern analysis of oil diagnostic results with service age of power transformers

Mineral insulating oil and cellulosic materials such as paper, pressboard, and cotton materials form the basic insulation system of ‘Oil filled transformers’. As the service-age increases these materials begin to deteriorate and may put the life of a transformer at stake. Besides normal aging, insulation degradation accelerates in presence of certain undesired factors. Power Transformers, being the most expensive equipment, are always in the foremost importance of utility's maintenance plan. In this regard, study of oil parameters is very important tool to monitor the health of transformers. Oil diagnostics tests like Oil quality analysis, Dissolved Gas Analysis and Furan analysis are well accepted tests to assess the condition of oil-paper insulation. Aging of oil-paper insulation follows a complex dynamic process. Oil sample results of 231 Power Transformers having different age and rating are examined thoroughly to get a particular trend/pattern for each parameter with age. This pattern analysis has emerged as an effective tool to have insights about the deterioration patterns of oil-paper insulation.