Assessing the Stability of Dielectric Properties and Viscosity of Natural Ester Oil Under Aging and Temperature Changes

This study investigates the impact of aging with oxygen and temperature on the physical and dielectric properties of soybean natural ester oil. Key parameters, including viscosity, relative content of dissolved decay products (DDPs), real part of relative permittivity, dissipation factor and conductivity, are analyzed for different aging periods (0, 164, 332, and 500 hours) and temperatures (20°C, 40°C, 60 °C and 80°C). Aging induces significant oxidative degradation, with both dielectric properties and viscosity increasing dramatically, the latter due to polymerization of by-products. Furthermore, the interactions between viscosity, real part of relative permittivity, dissipation factor and DDPs offer essential insights into the aging process and temperature-dependent behavior, which are crucial for optimizing the performance and extending the lifespan of transformers that use natural ester oils.