Pelton turbine is a type of impulse turbine which converts water energy (kinetic and potential energy of water) into mechanical energy. Later this mechanical energy can be converted into electrical energy with the help of an electrical alternator.
An impulse turbine is a type of turbine in which all the kinetic energy of water gets converted into mechanical energy of turbine by a direct impulse of water to turbine buckets. It is unlike reaction turbines (Kaplan turbine, Francis turbine etc.) where energy of water gets converted into mechanical energy of turbine in some stages.
Pelton wheel was invented by Lester Allan Pelton in 1870s.
There are few important points about Pelton turbines
- They require a water head of more than 300 meters for operation
- Their specific speed lies between 8.5 to 51
- They have power output of 10 to 300 MW
Working of Pelton turbine
Above image shows a cross sectional diagram of a Pelton wheel
Since a Pelton turbine requires a very high head for operation, it results into very high energy water jet. This jet is made to strike on the Pelton wheel. In a single impulse, all the kinetic energy of jet gets transferred to the Pelton wheel.
Pelton wheel is connected to a shaft. When wheel moves this shaft rotates. It means energy of water gets converted into mechanical energy of turbine.
Mechanical energy of turbine can either be used for generating electricity or it can be used for any other purpose.
Advantages of Pelton turbine
- It has simple construction
- It is east to maintain
- Intake and exhaust of water takes place at atmospheric pressure hence no draft tube is required
- No cavitation problem
- Its overall efficiency is high
- It can be both axial and radial flow
- It can work on low discharge
Disadvantages of Pelton turbine
- It requires high head for operation
- Turbine size is generally large
- Its efficiency decreases quickly with time
- Due to high head it is very difficult to control variations in operating head
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