What is an oil-filled transformer?

An oil-filled transformer, also known as an oil-immersed transformer, is a type of electrical transformer that uses liquid insulating oil as a cooling and insulating medium. This type of transformer consists of a core, primary and secondary windings, and an insulating oil that surrounds and cools the windings. The insulating oil serves several important functions in an oil-filled transformer:

Cooling: The oil helps dissipate the heat generated during the operation of the transformer. It absorbs the heat from the windings and transfers it to the transformer tank, where it can be released into the environment.

Insulation: The oil provides insulation between the windings and the transformer’s core, preventing electrical breakdown and ensuring safe operation.

Arc Suppression: In case of internal faults or short circuits, the insulating oil helps suppress the formation of electrical arcs and reduces the risk of fire or damage.

Pressure Relief: The insulating oil can expand and contract with temperature changes. To prevent excessive pressure buildup within the transformer, a pressure relief device or conservator tank is often used.

While oil-filled transformers have been widely used for many years due to their effective cooling and insulating properties, they do have certain disadvantages, such as the potential for oil leaks, environmental concerns related to oil disposal, and the fire risk associated with oil-filled equipment. These disadvantages have led to the development of alternative transformer technologies like dry-type transformers, which eliminate the need for liquid cooling and insulating mediums.