Dear friend, The Generator Transformer is designed based on the genartaing voltage. For ex. if the generating voltage is 11 kV and the national grid being 400 kV the GT will be 11/400 kV, 154 MVA Transformer. In case of 6.6 kV Voltage generation to step up to 220 kV, a 400 MVA Transformer is used since normally the state grid being 220 kV. The 11 kV side will be having a switchgear. For the exctiation an Unit Auxilary transformer normaly reffered as UAT will be used to give the exciatation. In some 220/6.6 kV station transformer will be used. Again it depends on the system design. A separate DC system will be there for the power house and a separate DC system for the 400 kV Switchyard protection system will be there. The GT will be having have separate protection system for the Generator and the transformer. The LV side will be having busduct and the HV side will be through ACSR conductor of suitable size depending upon the voltage. More precisely these concepts will be understood upon prcatial expereince. Regards N.Suresh