Study on the Compatibility of Natural Esters with Solid Materials for Transformers

During transformer operation, insulating oil interacts with internal solid materials. Compared with mineral insulating oil, the mutual reactions between natural ester insulating oil (NEIO) and solid materials exhibit greater complexity, making it imperative to investigate their compatibility and interaction mechanisms. This study systematically examines the property variations of NEIO and eight types of solid materials after 164 -hour thermal aging through compatibility experiments. Key parameters including kinematic viscosity (40° C), moisture content, acid value, dielectric dissipation factor (50 Hz), and breakdown voltage (ASTM D1816) of the oil were measured. The results demonstrate that although NEIO undergoes measurable changes during thermal aging, no significant degradation occurs. Concurrently, all solid materials maintain structural integrity and functional stability. This research establishes a theoretical foundation for selecting compatible insulating materials, optimizing insulation systems, and ensuring the reliable operation of NEIO-based transformers.