Effect of repeated electrical breakdowns on mineral and natural ester insulating oils

Transformer insulating oils are exposed to repeated electrical discharge or breakdowns inside power transformers. Durability tests conducted analyze the ability of oil resist decomposition due such high stresses. With increasing demand for alternative oil-immersed transformers, it is worthy compare performance different types (conventional mineral-based and natural ester-based oil) under breakdown. In this paper, AC breakdown voltage reported. were based on behavior after 50 shots. The each sample was assessed according ASTM D1816 standard test method. Based results, can be concluded that dissimilarity in chemical composition has a significant effect these breakdowns.