The Pelton turbine was developed by American inventor Lester Pelton. This turbine is most similar to the classical water wheel. With the Pelton turbine, the water lands in the middle of two half shells, the so-called buckets.
A Pelton rotor has 20 to 40 rotor buckets depending on the size. The water leaves one or many adjustable nozzles with high pressure on the blade between the half shells. The water jet is diverted almost 180° into the hollows of the blades. In this way the energy can be almost completely released over the turbines. The advantage of this type of turbine construction method lies in the drop-height. Pelton turbines are suitable for drop-heights of 50 to 1500 m. With a drop-height of 1000 m, the water jet can reach a speed of 500 km/h. The efficiency of this turbine is between 85 % and 90 %. As the drop-height plays an important role in Pelton turbines, such turbines are typically used in power plants situated in the mountains. Moreover, relatively small quantities of water are used. An important advantage of the Pelton turbine is that every single nozzle can be independently regulated, allowing fluctuations in the water quantity to be managed without problem. The Pelton turbine is classified in the category of constant-pressure turbine because the pressure before and after the power output at the turbine wheel is the same.