How does an oil forced air forced transformer cooling system work?

In OFAF cooling, pumps circulate oil through winding and core ducts and then through external coolers. Fans blow air across radiator or heat exchanger surfaces to remove heat from the oil. Forced oil improves heat transfer from internal hot spots, while forced air increases external heat rejection. Controls stage pumps and fans based on top oil or winding temperature, keeping temperature rise within design limits during peak loads.