Electric Field Simulation Analysis and Insulation Structure Optimization of Transformer Elevating Seat

During long-term operation, impurities and moisture in insulation oil would be absorbed by supporting parts in the elevating seat, which would reduce its insulation strength and leaded to partial discharge. In order to analyse the changing effect of the introduction of supporting parts on long oil gap E-field and optimize the insulation structure, based on the 500kV transformer, FEM was used to calculate the distribution of electric field in elevating seat, the equalizing ball shape was designed and optimized, the influence of elevating seat diameter on the lead surface maximum E-field was analysed. The results showed that after structural optimization, the maximum E-field on lead surface near supporting parts decreased from 8.95kV/mm to 7.82kV/mm, and on the equalizing ball surface decreased from 6.20kV/mm to 5.34kV/mm, with a decrease of 12.63% and 13.87% respectively, which improved the safety and reliability of transformer operation.