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The Pelton, Francis and Kaplan turbines are water turbines that are rotary machines which convert kinetic energy and the potential energy of the water into mechanical energy that rotates the shaft to produce electric energy.
Pelton turbine was developed by Lester Allan Pelton in the year 1870. A Kaplan turbine is a water turbine that was developed by Austrian Professor Viktor Kaplan in 1913 and Francis turbine was developed by James .B. Francis.
The basic difference between Pelton, Francis and Kaplan Turbines is explained in this article.
|Sl. No||Criteria||Pelton Turbine||Francis Turbine||Kaplan Turbine|
|1||Type||Pelton turbine is an impulse type water turbine||Francis Turbine is an inward flow reaction turbine.||Kaplan turbine is a propeller type reaction turbine.|
|2||Head||It is used for high heads ranging from 250 to 1000m||The operating water head of a Francis turbine ranges from 40 to 600m.||It is used for low heads ranging from 10 to 70 metres|
|3||Runner||The diameter of the runner varies from 0.8 to 0.6m||The diameter of the runner varies between 0.91 to 10.6||The diameter of the runner varies between 2 to 11 metres|
|4||Direction of Flow of Water Through the Blades||The flow of water is tangential to the runner. Hence it is also called as tangential flow impulse turbines||The flow of water through the blades combines both radial and axial flow.||The flow of water is axial through the blades.|
|5||Power Generation||Power generated is about 400MW||The power generated by a Francis turbine is about 800MW||The output power obtained varies from 5 to 200 MW|
|6||Speed||The rate of speed in a Pelton turbine changes from 65 to 800rpm||The speed of the turbine ranges from 75 to 1000rpm||The rotational speed varies from 69.2 to 429 rpm.|
|7||Discharge Required||The required discharge for the working of a Pelton turbine is low.||Medium discharge is required for the working of the Francis turbine.||A Kaplan turbine requires high discharge for efficient working.|
|8||Type of Energy||The Pelton turbines uses kinetic energy and converts into mechanical energy||The Francis turbine converts potential energy into mechanical energy||The Kaplan Turbine uses both kinetic and potential energy, which then is converted into mechanical energy.|
|9||Efficiency||The efficiency of a Pelton turbine is about 85%||The efficiency of a Francis turbine is about 90%.||The Kaplan turbine gives higher efficiency about 90%|
Table 1. Difference between Pelton, Kaplan and Francis Turbines
Features of Pelton, Kaplan and Francis Turbine
Features of Pelton Turbines
- Pelton turbines are used where the water source has a relatively high hydraulic head at low water flow rates.
- Pelton wheels can be designed for all sizes based on the objective.
Features of Kaplan Turbines
The important applications of Kaplan Turbines are:
- Electrical Power Production throughout the World.
- Suitable for lowest head hydro sites and high flow conditions.
- Kaplan turbines can work with as little as 0.3m head at a highly reduced performance given that sufficient flow exists.
- The design, manufacture, and installation is expensive but can operate for decades.
- Kaplan turbines designed individually for a site can give the highest possible efficiency of around 90%.
Features of Francis Turbines
- The Francis turbines operate best when its casing is completely filled with water at all times.
- It can be designed for a wide range of heads and flows.
- These turbines are not only used for electrical production, but also for the pumped storage.