DC current injection at high voltage potential allows adequate testing of HVDC components according to their later operation. Several concepts are possible. To achieve high current and high voltage ratings by stacking of several components, capacitive current injection is a reasonable concept. It consists of a feeding unit, the transmission path and the rectifier at high voltage potential. It is shown how the components can be built and which technical parameters are required inside the generator. The overall goal of the project is the upscaling of the concept up to 5000 A DC current on a high DC voltage potential of 660 kV. Challenges and solutions during the design phase of the upscaled generator are discussed. Pictures of the generator components are shown, as well as first experiences with the upscaled generator. Summarized, the contribution demonstrates that this generator concept for DC current injection at high voltage potential is technically feasible for high equipment ratings.