Differences Between Pelton Wheel & Kaplan Turbine & Francis Turbine?

Following are the differences between the Pelton wheel, Francis and Kaplan turbine:

1. Pelton wheel is an impulse turbine where static pressure head of water is converted into mechanical energy. On the other hand, Francis and Kaplan's turbines are reaction turbines where dynamic pressure head of water is converted into mechanical energy. In impulse turbine change in momentum gives the force applied on the buckets hence work done on the runner. But in reaction turbines blades are designed as a converging passage (in converging passage pressure of water decreases and velocity increases) between the blades, so pressure energy is converted to mechanical energy.
2. Impulse turbine is used where a high head is available. Francis turbine is for the medium head, and Kaplan is for the low head.
3. Similarly, Specific speed is inversely related to heads. So, for impulse turbine, specific speed is low, for Francis medium and Kaplan it is high.

Pelton wheel is used where a high head is available because as I said in the first point static pressure head of water is used in the Pelton wheel.

Francis turbine is a mixed flow type reaction turbine where both static and dynamic pressure head of water is used. So it is used where the medium head is available.

Kaplan turbine is an axial flow reaction turbine where the dynamic head of water is used. So it is used where the low head is available.