The turbo generators are fundamental power units inelectric power systems. So, improvements of selecteddesigning of large turbo generators, which enable toupgrade their nominal power to rise their operationalefficiency, reliability, safety and extending their lifetimeis an important subject. Applying varioustechnologies like lowering mechanical loss as well asequalizing temperature and electrical loss reduction,more efficient turbo-generators
are achieved. Differentstructures of stator bars including stator coil withtransposition in the slot/end portion, and stator windingwith strand to strand end connection have a great effecton circulating current loss, but end length limitationsand manufacturing complexity limits applying thesestructures. Stator coil structure with unequal crosssection of stator bars is presented in this paper as aneffective method for stray-load loss reduction in turbogenerators.