Pelton wheels are installed on

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Examoogle · Accepted Answer

High head plants

Explanation: Pelton wheels are impulse turbines specifically designed for high-head and low-discharge hydro-power applications. They convert the kinetic energy of a high-velocity water jet into rotational mechanical energy by striking buckets mounted on the periphery of a runner.

Working Principle: The water from a high-head source (penstock) passes through a nozzle, which converts the pressure energy into high-kinetic energy ($v = \sqrt{2gH}$). This high-velocity jet hits the split buckets of the runner at atmospheric pressure, causing the turbine to rotate. Since the buckets operate at atmospheric pressure, the turbine does not require a draft tube.

Key Formulas: $v = \sqrt{2gH}$ — Jet velocity based on head ($H$); $\eta = \frac{2(V_w - u)u}{V^2}$ — Hydraulic efficiency of the Pelton wheel

Key Points: Operates on the principle of Impulse turbine action.; Suitable for high head ($> 250$ m) and low water flow rate.; The runner always operates at atmospheric pressure.; Regulated by changing the needle position in the nozzle.

Advantages: High efficiency over a wide range of loads.; Simple construction and easy maintenance.

Disadvantages: Requires very high head which is not available everywhere.; Size of runner becomes bulky for low head applications.

Applications: High head mountain-based hydroelectric power plants.; Small scale micro-hydro projects with steep gradients.

Additional Info: Run-of-river plants are generally suited for low to medium head reaction turbines like Kaplan or Francis.. Base load plants typically use large reaction turbines like Francis or Kaplan due to their ability to handle large discharge volumes.

Answer: D is correct — Pelton wheels are impulse turbines specifically optimized for high-head, low-flow water sources.

Exam Tip: Always remember: Pelton = Impulse/High Head; Francis = Medium Head/Reaction; Kaplan = Low Head/Reaction.

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