An oil-immersed transformer is a type of electrical transformer that uses oil as an insulating and cooling medium. The transformer’s windings and core are submerged in mineral oil, which helps dissipate heat generated during operation and provides electrical insulation. This design enhances the transformer’s efficiency and longevity, making it suitable for high-voltage applications. Oil-immersed transformers are commonly used in power distribution systems due to their reliability and ability to handle large power loads.