The Kaplan turbine is a propeller-type water turbine which has adjustable blades. It was developed in 1913 by Austrian professor Viktor Kaplan, who combined automatically adjusted propeller blades with automatically adjusted wicket gates to achieve efficiency over a wide range of flow and water level.
The Kaplan turbine was an evolution of the Francis turbine. Its invention allowed efficient power production in low-head applications which was not possible with Francis turbines. The head ranges from 10 to 70 metres (33 to 230 ft) and the output ranges from 5 to 200 MW. Runner diameters are between 2 and 11 metres (6 ft 7 in and 36 ft 1 in). Turbines rotate at a constant rate, which varies from facility to facility. That rate ranges from as low as 54.5 rpm (Albeni Falls Dam) to 450 rpm.
