Short Answer:

The Pelton turbine works on the principle of converting the kinetic energy of a high-velocity water jet into mechanical energy using a set of specially shaped buckets mounted on a rotating wheel. The water jet strikes the buckets, causing the wheel to rotate and generate power.

This turbine is mainly used in high-head, low-flow hydroelectric power plants. The high-pressure water is released through nozzles as fast-moving jets, which hit the curved buckets, transferring momentum and making the runner spin. This rotating motion is then used to drive generators for producing electricity.

Detailed Explanation

Working Principle of a Pelton Turbine

The Pelton turbine is an impulse-type hydraulic turbine used mainly for converting the kinetic energy of water into mechanical energy in high-head hydropower projects. It was invented by Lester Pelton in the 19th century and remains widely used in mountain regions or where water is available at high elevation with low flow rates.

The basic idea behind the Pelton turbine is simple but very efficient: water stored at a height contains potential energy, which is converted into kinetic energy by releasing it through narrow nozzles as high-speed jets. These jets hit spoon-shaped buckets mounted on the edge of a wheel called the runner. The impact of the water jet applies a force that causes the runner to rotate. This mechanical rotation is used to generate electricity by connecting the runner to an electric generator.

Key Components

1. Nozzle and Spear:
   The nozzle converts pressure energy into a high-velocity jet. A spear inside the nozzle controls the flow of water based on the load requirement.
2. Runner and Buckets:
   The runner is a wheel with double-cupped (split) buckets. When the water jet hits the buckets, it divides into two parts, allowing efficient energy transfer and reducing the force acting against the wheel’s motion.
3. Casing:
   Although it doesn’t help in pressure control (as it does in reaction turbines), the casing in a Pelton turbine helps in preventing water splashing and directing spent water safely out of the system.
4. Brake Nozzle:
   This secondary nozzle releases water on the back side of the runner to stop it quickly when needed.

Working Process

• Water from a high-altitude reservoir is transported through a penstock to the turbine.
• At the end of the penstock, nozzles convert the potential energy into a high-velocity jet.
• The jet of water is directed onto the buckets of the runner.
• The shape of the buckets allows the jet to split and change direction by almost 180°, maximizing momentum transfer.
• The runner spins, converting kinetic energy into mechanical energy.
• This mechanical energy is used to rotate a generator shaft and produce electricity.

Conditions for Efficient Operation

• High water head (usually more than 300 meters).
• Clean water to prevent erosion of nozzles and buckets.
• Proper alignment between jet and bucket for full energy transfer.
• Controlled flow through spear valves to match load demands.

Conclusion

The working principle of a Pelton turbine is based on converting the kinetic energy of a high-speed water jet into mechanical rotation by striking specially designed buckets on a wheel. It is highly efficient for high-head, low-flow conditions and plays a key role in hydroelectric power generation. Proper design and installation of components like nozzles, buckets, and runners ensure smooth energy conversion and long-term performance.