An oil-filled transformer is a type of transformer used to change the voltage level of electrical energy and uses a special insulating oil for cooling and insulation. Oil-filled transformers are usually filled with mineral oil or synthetic insulating oil. This oil provides electrical insulation and also acts as cooling to prevent the transformer from heating up. This oil absorbs the heat generated by the coils and magnetic core and dissipates it through cooling radiators or cooling fans. Oil-immersed transformers provide high efficiency even at high loads. This minimizes energy losses and ensures long-lasting performance.