What requirements are specified in IEC 60296 transformer oil standard?

IEC 60296 defines requirements for unused mineral insulating oils used in transformers and switchgear. It typically specifies performance classes and limits for key properties such as dielectric strength, moisture content, acidity, dielectric dissipation factor, resistivity, density, viscosity, flash point, and oxidation stability. It also addresses inhibitor status for inhibited oils and may include additional quality criteria related to corrosive sulfur and appearance. In procurement, utilities reference IEC 60296 to ensure new oil quality before filling or topping up equipment.