Performance conversion methods for hydraulic turbines and pump-turbines have been established as international and domestic standards to transpose from the model performance to the corresponding prototype performance. The up-to-date standards and their performance conversion take into account of the surface roughness of each flow passage component of machines. As a result, the performance conversion methods came to include the complicated calculation and its procedure. Therefore, the simplification of performance conversion methods has been expected by the users and engineers from the practical point of view. In this study, the performance conversion method is simplified considering the general capacity of measuring devices in model test equipment used by domestic manufacturers and the typical surface roughness of the flow passage components of prototype machines.
