How do mineral-oil transformers dissipate heat and maintain dielectric strength?

Heat is transferred from windings to oil, then to radiators or cooling banks where it is released to air or water. Natural convection systems rely on oil circulation from density differences, while forced systems use pumps and fans to increase heat transfer. Dielectric strength is maintained by keeping oil dry and clean. Moisture removal, filtration, degassing, and oxidation control prevent breakdown voltage reduction. Sealing, breathers, and conservators reduce contamination from ambient air.