The Pelton Wheel was invented by Lester Allen Pelton in the United States in the 19th century, it is an impulse turbine that usually is used in a high head system. The Pelton Wheel spins from the force of the momentum of high head flowing water.
The Pelton Wheel is an impulse turbine instead of a reaction turbine. A reaction turbine would use the weight or pressure from the water to move the turbine, but an impulse turbine uses the momentum and force of moving water to turn the turbine.
Another revolutionary feature developed by Lester Pelton was that he placed a metal divider at the point where the flowing jet of water hits the blades. This divider splits the stream of water into two separate streams. When the split steam of water hits the turbine blade, the turbine spins will spin faster than if the jet of water was still a single stream.
The Pelton Wheel is a very efficient hydro turbine wheel and is still commonly used today because it is very versatile with various hydropower systems. The pelton wheel can be used with a very small turbine with a high head & low volume of water, or can be used with a very large, high output hydro turbine. Although it is versatile, the Pelton Wheel is still usually used in a high head system with a low flow of water.