How does insulating oil improve dielectric performance in transformers?

Insulating oil improves dielectric performance by increasing the breakdown voltage between energized components and ground. It fills voids and air gaps inside the transformer, eliminating partial discharges that can occur in air-filled spaces. The oil also absorbs and dissipates electrical stress more uniformly across insulation surfaces. Additionally, transformer oil helps remove moisture from solid insulation such as paper and pressboard, which significantly enhances dielectric strength. Clean, dry oil is therefore essential for maintaining high insulation reliability and preventing electrical faults.