Insulation Design Analysis for Natural Ester Oil Power Transformers

This study investigates the insulation design of high-voltage transformers using natural ester oil as an alternative to traditional mineral oil. A 115 kV power transformer provided by TTM for PEA, operating with mineral oil, serves as the research subject. Voltage distribution and oil duct voltage gradient under full-wave lightning impulse are calculated for the high-voltage winding to assess the safety margin of minor insulation using both natural ester and mineral oil. Additionally, a finite element method (FEM) analysis is conducted to evaluate the major insulation system's electric field distribution under full-wave lightning impulse voltage for both cooling media. Comparative analysis between natural ester and mineral oil insulation designs is performed, highlighting differences and providing insights for optimizing natural ester transformer insulation.