Question

Explain with a neat sketch the construction and working of Pelton turbine used in hydro power plant.

Answer 1

Could you specify which aspects of the Pelton turbine you're most interested in? For example, are you looking for details on its construction, working principle, or its applications?

Answer 2

### Pelton Turbine: Construction and Working

The Pelton turbine, or Pelton wheel, is a type of impulse turbine used primarily in hydroelectric power plants where high head and low flow conditions are prevalent. Here's a detailed explanation of its construction and working, accompanied by a simple sketch.

#### Construction of Pelton Turbine

1. **Wheel (Runner):**
   - **Description:** The Pelton wheel is a circular disc mounted on a horizontal shaft. It has a series of spoon-shaped buckets (also known as cups) evenly spaced around its perimeter.
   - **Material:** Typically made from high-strength materials like steel or cast iron to withstand the high impact of water jets.

2. **Buckets:**
   - **Description:** Each bucket is designed with a split or "V" shape, which splits the water jet into two streams. This helps to maximize the energy transfer from the jet to the bucket.
   - **Arrangement:** The buckets are positioned tangentially around the wheel. This arrangement allows the wheel to capture and utilize the energy of the water jet effectively.

3. **Nozzle:**
   - **Description:** The nozzle directs the high-pressure water flow onto the Pelton wheel. It is often adjustable to control the flow rate and optimize turbine performance.
   - **Function:** Converts the potential energy of water into kinetic energy by accelerating it into a high-velocity jet.

4. **Guide Vanes:**
   - **Description:** These are used to direct the water flow towards the nozzle.
   - **Function:** They ensure that the water jet strikes the buckets at the optimal angle.

5. **Casing:**
   - **Description:** The casing encloses the Pelton wheel and the nozzle assembly.
   - **Function:** It protects the turbine from environmental factors and helps in directing the water flow.

6. **Shaft:**
   - **Description:** The horizontal shaft is connected to the Pelton wheel and transmits the mechanical energy generated by the wheel to the generator or other machinery.
   - **Function:** It transfers the rotational motion of the wheel to the generator for power generation.

#### Working of Pelton Turbine

1. **Water Flow:**
   - Water from the reservoir or penstock is directed towards the nozzle. The water pressure is high due to the elevation difference, which converts potential energy into kinetic energy.

2. **Jet Formation:**
   - The nozzle accelerates the water, forming a high-speed jet. This jet is directed towards the buckets of the Pelton wheel.

3. **Energy Transfer:**
   - The high-velocity water jet strikes the buckets at a tangential angle. The bucket's shape splits the jet, and the force of the water impacts the bucket, causing the wheel to rotate.

4. **Rotation of the Wheel:**
   - As the wheel rotates, it continues to capture the energy from successive water jets. The rotational motion of the wheel is transferred to the shaft.

5. **Power Generation:**
   - The rotating shaft is connected to a generator, which converts the mechanical energy into electrical energy.

6. **Water Discharge:**
   - After passing through the buckets, the water jet is discharged into a tailrace or downstream area.

### Sketch of Pelton Turbine

Here is a simplified sketch to illustrate the construction and working of the Pelton turbine:

```
          _______
         /       \
        |  Nozzle  |----> (High-Velocity Jet)
         \_______/
              |
              |
        ________|________
       |    Guide Vanes   |
       |__________________|
            \   |   /       
             \  |  /        
              \ | /         
               \|/            
             ____________
            |            |
            |  Pelton    |
            |   Wheel    |
            | (Buckets)  |
            |____________|
                 |
                 |
              _____
             |     |
             | Shaft|
             |_____|
                |
              Generator
```

### Key Points

- **High Head, Low Flow:** Pelton turbines are ideal for sites with high elevation (head) and relatively low water flow.
- **Efficiency:** They are highly efficient because they can handle large changes in water velocity, and the water jet's energy is transferred efficiently to the wheel.

By converting high-pressure water energy into rotational energy through the Pelton wheel, the turbine generates mechanical power that can be transformed into electrical energy. This makes it a crucial component in many hydroelectric power plants.