High heads(350 m and above): Pelton turbine Reaction turbines not suitable (losses) Medium heads: Francis turbine (sometimes impulse turbines can also be used) Low heads(below 60 m): Propeller type of turbine is used.
Hydrological Data: „ The maximum working head „ The design Head „ The design discharge Available discharge Speed and nature of load
Type of turbine:(for e.g. adjustable blade axial flow turbine or akaplan turbine) The power generated( in bhp): Diameter of the hydraulic turbine Rotational speed
Spiral casings are either made of metal for headsranging from 40 to over 200m or of concrete forlow and medium heads, i.e. up to 75m
The role of the draft tube is to convert kineticenergy into pressure energy with a minimum oflosses Straight conical draft tube Elbow draft tube
A propeller-type runner rated 28,000 hp (21 MW)
Vertical shaft: (for reaction turbines) Great variations of tail water level Deep foundations, as the weight of the rotating parts acts in the same direction of the axial hydraulic thrust Horizontal shaft: (for impulse turbines) Grouping of two or more runners can be done Foundations are not that deep, but occupy more surface area