A Study on the Insulation breakdown voltage according to degradation condition of natural ester oil

This study investigates the degradation characteristics and dielectric strength of natural ester oil and impregnated insulating paper, comparing them with conventional mineral oil for eco-friendly transformers. An accelerated deterioration test was conducted using two sample sets subjected to different insulation oils. The degradation behaviors of insulation paper in natural ester oil were compared with those in mineral oil. Results indicate a slower degradation rate in natural ester, with a 27% decrease even after 8,000 hours, compared to a 58% decrease in mineral oil at 3,500 hours. Additionally, the AC breakdown voltage of natural ester oil remains above 60 kV at a 2.5 mm gap, even with increased water content (330 ppm), showcasing its higher moisture tolerance than conventional mineral oil.