Natural ester insulating oils has the advantages of good biodegradability, high flash point, low carbon emissions and fire protection, and is a  good alternative to non-renewable mineral insulating oils. However, due to the inherent molecular structure, its oxidation stability is much lower than that of mineral insulating oils. The industry has improved the oxidation stability of natural ester insulating oil by adding antioxidants, and formulated corresponding new oil selection guidelines. However, the consumption of antioxidants in the operation and maintenance process has not yet put forward a practical standard, which brings great confusion to equipment operation and maintenance engineers. In this paper, the quantitative detection of DBPC, a typical antioxidant DBPC, is realized by high performance liquid phase and gas chromatography mass spectrometry, and the repeatability and extraction rate of the method are studied, which provides a feasible operation and maintenance method for the operation and maintenance of transformer impregnated with natural ester insulating oil in operation.

Nature ester; Antioxidant; HPLC; GC-MS