... Combined transformers Combined transformer is composed of body, switches equipment, fuse, tap-changers,all together in a sealed full oil transformer ... bushings, on-load tap changer, off-circuit tap changer, inset fuse, pressure relief valve,oil indicator, thermometer, oiling plug. In the ... : A, four pole type construction core, fuse and L.V. winding are connected in series as a phase unit to form a D ...