Stray gassing of transformer insulating oils: impact of materials, oxygen content, additives, incubation time and temperature, and its relationship to oxidation stability

For many years, dissolved gas analysis (DGA) has been considered worldwide as the most important technique for evaluating the state of health of oil-filled power transformers. Based on regular analysis and trending of the dissolved gases extracted from insulating oil samples, an assessment can be made whether internal transformer abnormalities are present and how critical these abnormalities are [1], [2]. The article examines the impact of temperature, oxygen, antioxidant, and incubation time on stray gassing of unused and in-service mineral oils and the relationship of gassing to oxidation stability.