What is transformer oil used for in oil-filled transformers?

Transformer oil is used for in oil-filled transformers primarily as an insulating and cooling medium. It provides electrical insulation between live components and helps dissipate heat generated during operation. The oil’s high dielectric strength prevents electrical breakdown, while its thermal conductivity ensures efficient heat transfer away from the transformer core and windings, maintaining optimal operating temperatures and enhancing the overall reliability and longevity of the transformer.