(US4487549-A)      The appts. has a speed detector for detecting the speed of the hydraulic machine. A comparator compares the detected speed signal with a speed command to produce a stroke signal in accordance with a speed deviation signal obtained through the comparison.    Guide vanes associated with any selected runner opened and closed by a driver in accordance with the stroke signal. The stroke signal generator is connected to the driver for the guide vanes associated with the other runner or runners so that a predetermined relationship is maintained between the opening degree of the guide vanes of the selected runner and the opening degree or degrees of the guide vanes associated with other runner or runners.    ADVANTAGE -   Has reduced no. of control elements to ensure high control reliability. Runners share equal parts of total heads. (12pp)v    (EP67453-B)      An apparatus for controlling the operation of a hydraulic machine (1) having a plurality of runners (3, 4) mounted in series on a common shaft (2) connected by a common raceway and movable flow rate adjusting vanes (8, 9) arranged around respective runners so as to adjust the flow rate of water to respective runners, said apparatus comprising: a single governer constituting revolving speed detection means (17) for detecting the revolving speed of said hydraulic machine (1); a single stroke signal generating means (78) adapted to compare the detected revolving speed signal (14) with a revolving speed command (71) to generate a stroke signal (S02) in accordance with a revolving speed deviation signal (S01) obtained from said comparison; first opening and closing means (20, 40) for drivingly opening and closing said movable flow rate adjusting vanes (8, 9) arranged around any selected one of said runners (3, 4) in accordance with said stroke signal; second opening and and closing means (20, 40) for opening and closing said movable flow rate adjusting vanes (8, 9) arranged around the remainder of said runners (3, 4); and cam means (80) for connecting said stroke signal generating means (76) to said second opening and closing means (20, 40) associated with the remainder of said runners (3, 4) to provide a predetermined relationship between the opening degree of said movable flow rate adjusting vanes (8, 9) arranged around said selected one of said runners (3, 4) and the opening degree or degrees of said movable flow rate adjusting vanes (8, 9) arranged around the remainder of the runners, the profile of said cam means (80) for providing the predetermined relationship between said flow rate adjusting vanes (8, 9) arranged around one of said runners and said movable flow rate adjusting vanes (8, 9) arranged around the remainder of the runners being determined such that the guide vanes of all stages are controlled in synchronism such that the total head over the turbine is