manually or automatically controlled. The cooling class designation for this type of transformer is OA/FA.
Forced air cooled and forced oil cooled: This transformer uses a pump to circulate oil through a heat exchanger to increase heat dissipation, which supplements the self-cooling and forced air cooling. The cooling class designation for this transformer is OA/FA/FOA.
Water cooled: This transformer uses water instead of air to provide the cooling. The cooling system consists of a heat exchange by means of water pumped through a pipe coil installed inside or outside the transformer tank. The cooling class designation for this transformer is FOW.