Francis turbine with generator. (Source: © Filipp / stock.adobe.com)

A very common water turbine with movable guide vanes but fixed runner blades, which is rotated by the difference in water pressure at the inlet and outlet (reaction turbine). It is often used in pumped storage plants. The Francis turbine is suitable for heads between 20 and 700 metres and wide flow ranges. The runners of Francis turbines installed in the biggest hydroelectric power plants in the world can have a diameter of more than 10 metres.