Study on Lifespan Prediction of Oil–Paper Bushing Considering the Influence of Moisture-Accelerated Aging

Abstract

The moisture-dependent parameter in the aging kinetic model is inaccessible due to the fluctuation of moisture during the aging period of bushing insulation. This significantly restricts the adoption of aging kinetics-based approaches for predicting transformer bushing insulation lifespan. Given this issue, an improved aging kinetic model is proposed in this article, where the influence of moisture fluctuation is interpreted by the moisture acceleration coefficient. To obtain the involved parameters in the improved model, the humidity of bushing insulation is determined by recognizing the moisture-related feature, which can be extracted from the logarithmic-derivative method derived from frequency domain spectroscopy (FDS). Finally, the improved aging kinetic model and logarithmic-derivative method are then used to provide a method for predicting the lifespan of bushing insulation. According to verification experiments carried out with this model, the relative errors of the re-created laboratory samples are 8.12%, 8.89%, and 25.15%, respectively. In that regard, this article is likely to serve as a model for predicting the lifespan of oil–paper insulation on genuine condenser bushings.