What requirements are defined in transformer insulating oil specifications?

Specifications define dielectric strength, moisture limits, acidity, dielectric dissipation factor, resistivity, interfacial tension, viscosity, density, oxidation stability, flash and fire points, and corrosive sulfur behavior. They also define cleanliness, inhibitor content if inhibited, and acceptance testing for new oil. Some specifications include compatibility requirements with paper insulation and gaskets, plus guidance for handling and storage. Compliance is confirmed by certificate of analysis and standardized testing, ensuring the oil provides reliable insulation and cooling throughout the expected service conditions.