Moisture detection of oil-immersed bushing insulation based on color level analysis

The operational level and service life of oil-immersed bushings are related to the moisture content in their cellulosic insulation layers. The authors proposed a novel method based on Taylor series modeling and grey relational analysis to assess the moisture content in the cellulosic insulation of oil-immersed bushings. Unlike conventional methods relying solely on frequency domain spectroscopy (FDS) data from certain frequency ranges, this method uses Taylor series to model the full spectrum and extracts a set of moisture-related feature parameters, thus avoiding dependence on specific measurement points or ranges. To establish the relationship between feature parameters and moisture levels, a database was constructed in this study. Grey relational analysis was used to propose an alternative method for assessing the moisture in bushing cellulosic insulation. Results show the average relative error between the estimated and measured moisture was less than 15.7%. Overall, the proposed method in this study provides an effective approach for assessing the moisture in the cellulosic insulation of oil-immersed bushings.