This part of IEC 62271 is applicable to single- and three-phase direct connections between gas-insulated metal-enclosed switchgear (GIS) for rated voltages above 52 kV and transformer arrangements to establish electrical and mechanical interchange ability and to determine the limits of supply for the transformer connection. Direct connections are immersed on one end in the transformer oil or insulating gas and on the other end in the insulating gas of the switchgear. Transformer arrangements are single-phase transformers with single-phase enclosed arrangement, three-phase transformers with three single-phase enclosed arrangements or three-phase transformers with a three-phase enclosed arrangement with three transformer bushings. The connection satisfies the requirements of IEC 62271-203 for gas-insulated metal-enclosed switchgear, IEC 60076 for power transformer and IEC 60137 for completely immersed bushings. For the purposes of this document the term "switchgear" is used for "gas-insulated metal-enclosed switchgear".