Method to Estimate the Moisture Content of On-board Traction Transformer in EMUs

Moisture is a crucial factor that significantly impacts the insulation condition of oil-paper insulation in transformers. In engineering practice, the moisture content of insulation paper is primarily obtained indirectly using moisture equilibrium curves and moisture calculation models of oil-paper insulation. The aging status of insulation paper exhibits discernible impacts on its moisture absorption characteristics. In this study, the widely adopted moisture calculation model in engineering and related research, i.e., the Fessler model, was optimized by considering the influence of the aging status. Furthermore, the optimized model was verified by comparing the calculated results with experimental data. The optimized model provides a fundamental basis for further research and practical applications in engineering.