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Consider the following statements: 1. Surge tanks are not substitute for forebays. 2. Pumped storage power plants are a boon to power generation. 3. Water hammer in penstocks is not dangerous. 4. Kaplan turbines are used in low head power plants. Which of the above statements are correct?

Consider the following statements: 1. Surge tanks are not substitute for forebays. 2. Pumped storage power plants are a boon to power generation. 3. Water hammer in penstocks is not dangerous. 4. Kaplan turbines are used in low head power plants. Which of the above statements are correct? Correct Answer 2 and 4 only

Concept:

A surge tank is used to prevent a sudden increase of pressure in the supply line or penstock. It is placed as near as possible to the turbine. The tank may be opened at the top or closed. In case it is open at the top, it must not be lower than the level of the water in the reservoir.

A forebay is a basin area of hydropower plants where water is temporarily stored before going into the intake chamber. The storage of water in forebay is decided based on the required water demand in that area. This is also used when the load requirement in intake is less.

So Surge tanks can be a substitute for forebays.

Pumped storage plants are employed at the places where the quantity of water available for power generation is inadequate. Here the water passing through the turbines is stored in ‘tail race pond’. During low load periods, this water is pumped back to the head reservoir using the extra energy available. So it is a boon to power generation.

A water hammer is due to a sudden increase of pressure in the supply line or penstock. So it is dangerous for penstock.

Kaplan turbines are axial flow turbines that are used in low head and high discharge power plants.

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