Impregnation Mechanism of Synthetic Ester - Aramid Pressboard Composite Insulation System

The utilization of a novel composite insulation system comprising high-permittivity aramid paper and synthetic ester can endow transformers with enhanced overload capacity, thereby addressing impacts arising from the randomness, intermittency, volatility, and uncertainty of power systems. This paper specifically investigates the impregnation characteristics of synthetic ester-aramid paper composite insulation. Based on an analysis of the impregnation mechanism of synthetic ester into aramid paper, a quantitative model for predicting the impregnation rate under varying pressures, temperatures, as well as for aramid papers with different porosities and pore sizes, is proposed. An experimental impregnation model for synthetic ester-aramid paper insulation is designed, through which the relationship between impregnation height and time in single-layer aramid papers of different densities is empirically established. Key factors influencing the impregnation process of this new oil-paper insulation system are discussed, and the accuracy of the theoretical model is validated. Furthermore, an impregnation test model for laminated aramid paperboard is developed, and a method for improving its impregnation rate is proposed. Impregnation tests conducted at pressures of 0.3–0.6 MPa and temperatures of 20–100 °C demonstrate the resulting change in impregnation rate before and after optimization, confirming the effectiveness of the improved process. This study provides material-level fundamental data support for the impregnation process in the industrial manufacturing of synthetic ester-aramid insulated power transformers.