Basically there are three types of turbines: steam, gas, and hydel. Here, the turbines have been classified by the type of fluid they handle—that is, steam or gas (hot air), water, etc. Gas turbines have been briefly discussed in Clause 2.4
. The hydel turbine is a type that operates on the principle of high-velocity water coming from a source located at a higher elevation through a pipeline impinging on the turbine impeller. The steam turbine utilizes high-pressure and high-temperature steam as the prime moving force and is discussed briefly next.