What parameters define transformer oil specifications?

Transformer oil specifications define dielectric strength, moisture content, acidity, dielectric dissipation factor (tan delta), resistivity, viscosity, density, flash point, oxidation stability, and corrosive sulfur behavior. Standards may also specify inhibitor content and appearance. These parameters ensure the oil can provide reliable insulation, effective cooling, chemical stability, and safe operation throughout the transformer’s service life under expected electrical and thermal stresses.