Arrangement and method for testing an electric power generation system

It is described an arrangement for testing an electric power generation system, in particular a wind turbine system, being connected to an utility grid providing a predetermined first voltage, the arrangement comprising: a input terminal (113, 313) for connecting the arrangement to an output terminal (116, 316) of the power generation system; a grid terminal (102, 302) for connecting the arrangement to the utility grid (101, 301); a transformer (105, 305) temporarily connectable between the input terminal and the grid terminal, wherein the transformer is adapted to transform the first voltage (U1) to a second voltage (U2) which is different from the first voltage; and a measurement system (119, 319) adapted for measuring a current flow through the input terminal. Further, a corresponding method is described.