They are used at generator step up points in power plants, transmission substations, interconnection nodes, and major distribution substations. Oil power transformers handle high voltage transformation such as stepping from transmission to subtransmission, and from subtransmission to medium voltage distribution. They are typically installed outdoors in switchyards or fenced substations with containment and fire safety systems. Their role is core to moving bulk power efficiently across long distances and delivering reliable voltage levels to regional networks and large industrial loads.