What are the primary transformer oil uses in power systems?

Primary uses are dielectric insulation and heat transfer in oil immersed transformers. Oil also supports arc suppression and reduces partial discharge by filling voids. It protects paper insulation by limiting oxygen exposure in sealed systems, and it enables diagnostics because fault gases dissolve in oil for DGA monitoring. In addition, oil supports mechanical damping and reduces hot spot gradients by distributing heat. Maintaining oil quality is a major reliability activity in utility and industrial power systems.