Model to estimate solid insulation ageing in power transformers via alcohol based chemical indicators

Service life of a transformer is dependent on the life of oil-paper insulation system. To ensure the healthiness of transformer, both maintenance and diagnostics play an important role. This paper highlights advantages of using the methanol and ethanol as an early-stage ageing indicator and abnormal ageing indicator respectively over the conventional indicators (e.g., Furan, Dissolved Gas Analysis (DGA)). In present work, insulation paper ageing analysis of more than 100 nos. operational transformer have been performed. Further, effect of oil temperature on the generation of methanol and ethanol from insulation paper were also studied. As methanol and ethanol are volatile compounds, therefore their stability under atmospheric condition have been performed to formulate the standard operating procedure (SoPs) during measurement. Additionally, methanol and ethanol analysis have been compared and/or correlated with DGA and furan measurement to analyse the healthiness of oil-filled equipment.