A 11kV oil distribution transformer is a transformer that provides a final voltage transformation in the electric power distribution system, stepping down the voltage used in the distribution lines to the level used by the customer. A hermetically sealed oil transformer is a type of electrical transformer that uses a liquid, such as oil, as a cooling and insulating medium. It is also known as a liquid transformer.

Oil provides excellent dielectric insulation and helps to prevent the corrosion of internal components. It is important to note that oil-filled transformers require regular maintenance and may pose an environmental hazard in the case of oil leaks or spills.