The Kaplan turbine is an Austrian invention by Viktor Kaplan and is chiefly used for large masses of water and low drop heights. The rotor is similar to a ship's propeller. Fitting it takes place mostly vertically, so that the water can flow over the turbine from top to bottom.
Directly above the turbine is the generator. The generated kinetic energy is transferred from the turbine to the generator with the help of a vertical shaft. The Kaplan turbine is characterised by its adjustable turbine rotor blade and propeller. With this, the Kaplan turbine can be adjusted optimally to fit the amount of water and the drop height. Thus 80-90% efficiency can be attained. The Kaplan turbine's field of use is in hydraulic power stations, because these types of turbines also work well at low drop heights and fluctuating rates of flow. The water pressure constantly decreases from the moment it enters the rotors till when it leaves them, therefore, this turbine falls into the reaction turbine category.