How does an oil cooled transformer dissipate heat under load?

An oil cooled transformer dissipates heat by transferring thermal energy from the windings and core into the insulating oil. As the oil heats up, it becomes less dense and rises toward the top of the tank, flowing into radiators or cooling fins where heat is released to ambient air. Cooler oil then sinks back toward the windings, creating natural circulation. In higher rated units, pumps and fans assist this process. Effective oil circulation prevents hot spots, reduces insulation aging, and maintains stable operating temperatures under heavy load conditions.