What requirements are defined in the IEC 60296 transformer oil standard?

IEC 60296 sets acceptance limits and classification rules for unused mineral insulating oils intended for electrical equipment. It defines required property values and test methods for parameters that determine dielectric performance and long term stability, such as BDV, moisture, acidity, dielectric loss, resistivity, viscosity, density, flash point, and oxidation behavior. It also distinguishes inhibited and uninhibited oils and includes quality expectations that support safe filling and operation. Utilities use it as a baseline to qualify new oil deliveries and supplier batches.