with retroactive action

Full Title

Controlling (controlling in general G05 ) > by varying liquid flow > of turbines (rotors having adjustable blades F03B3/06, F03B3/14; adjustable guide vanes F03B3/18; specially adapted for turbines with jets of high-velocity liquid impinging on bladed or like rotors F03B15/20) > Regulating, i.e. acting automatically > by speed, e.g. by measuring electric frequency or liquid flow > with retroactive action