Abstract: A process and apparatus for preventing the overspeed of a low head hydroelectric generating set including a turbine having an adjustable distributor valve assembly and adjustable vanes wherein the openings of the valve assembly and vanes are continuously monitored relative to one another and with the openings of the valve being limited by a conjugation device so as to insure that the pressure head through the turbine is retained at or just slightly below the normal lowest operating pressure head for which the turbine is designed to operate.

Abstract: Low-head hydroelectric installation, in particular for a tidal power station, intended to operate under variable heads of water that can fall to values in the region of zero. When the head of water is lower than a defined value (Hd), lower than at least half the nominal head (Hn), the turbo-machine (1) is made to rotate at a speed (n1, n2, n2, . . . ) lower than the synchronous speed (ns) and bringing its efficiency near to the heart of the efficiency contours. For this purpose, a frequency converter (7) is inserted between the rotary electrical machine (3) and the network (4), the converter (7) being constructed for a power in all cases lower than at least half the nominal power (Pn).

Abstract: A method of controlling the operation of a water turbine, in particular a bulb type turbine, wherein the mobile guide vane assembly serves only to reflect the water during operation, the starting and stopping of the turbine being controlled and water-tight sealing when the turbine is stopped being provided by a gate sluice.