This paper deals with the design and construction of a rotating contactless energy transfer system. The system is used to replace the slip rings of an electrical excited synchronous machine and transfer energy contactless on the rotor of the machine. Considering the application and the involved boundary conditions, three approaches with non distinctive magnetic flux guidance of the electromagnetic design are presented. Calculation and dimensioning of the system is done by electromagnetic and thermal 2D and 3D finite element simulation. Finally, the results are verified by prototypes, constructed for each presented approach.