What are the quality requirements for transformer oil?

The quality requirements for transformer oil include low moisture content (typically below 0.1%), high dielectric strength (minimum 30 kV for new oil), and low acidity (less than 0.1 mg KOH/g). Additionally, the oil should have a high flash point (above 140°C) and low levels of dissolved gases to minimize the risk of electrical breakdown. Regular testing for oxidation stability and the presence of contaminants is also essential to ensure optimal performance and longevity of the transformer.