A search is undertaken to obtain optimal settings for hydraulic turbine governors in isolated operation. The scope of this optimization process is to maximize the stability margins of the closed frequency control loop. The settings obtained are very close to those suggested by the classical Paynter formulas. Then a regulating capacity chart is derived that gives, for different values of the water starting time, the necessary minimum mechanical inertia constant of an autonomous hydroelectric unit, so that the frequency of the system can be properly controlled.<<ETX>>