Selection of Speed of Pelton Turbine

Specific speed of the Pelton turbine ranges from 10 to 35. If the speed of the turbine is made higher, following changes may be required:

• Specific speed of turbine will increase.
• Size of turbine will increase.
• The jet diameter will decrease to increase the jet ratio and turbine efficiency.
• Multiple jet will be required; the governing of multiple jet becomes complex.
• The number of pole required in the generator coupled with the turbine will be less due to high speed.

Hydraulic Brake: To stop the turbine quickly in short interval of time, some smaller nozzles are fixed in such a way that water jets strike the bucket from back side.