- Functional Principle
- Action Turbines: converts the potential energy into kinetical energy before the water's acces onto the runner (Impulse, also called Pelton). The rotor of the action turbine is spining in the air, and it doesn't have to be sunk (underwater).
- Reaction Turbines converts into different proportions both kinetical and potential energy and we find in this category radial-axial turbines (Francis), and axial turbines type (Kaplan and Bulb).
- Speed (n)
- low: 2 ÷ 100 rpm (Kaplan, Bulb)
- medium: 50 ÷ 400 rpm (Francis)
- high: 400 ÷ 1200 rpm (Pelton)
- Specific Parameters Values: Flow Q [m3/s] and Head H [m]
- For high and very high head (greater than 600 m or 1800 feet) and low flow (mountain harnessing) there are usually used Pelton turbines, which already reached power up to 300,000 kW. For large power the solution is a turbine with vertical shaft and 5 or 6 nozzles.
- For medium to high head (between 400 and 600 meters or 1200 and 1800 feet) and medium flow (mountain harnessing) there are used Francis turbines, reaching power over 700,000 kW.
- For low head and high and very high flow (run-of-river power plant) Kaplan (under 40 meters or 120 feet) and Bulb (under 15 meters) turbines are the ideal solution. Kaplan turbines reach powers up to 250,000 kW, and Bulb up to 55,000 kW.
- Shaft's Position
- horizontal shaft (any type of turbine)
- vertical shaft (any type of turbine, but Bulb)
- inclined shaft (usually Bulb)
The link between the turbine's specific parameters and the facility, based upon scientific criteria, allows it's building with optimal investments and an operation with a maximum efficiency and minimal costs.