Hydraulic Machines MCQ with answer and solution

Concept

The surge tank acts as a pressure relief valve and a storage reservoir to manage sudden changes in flow velocity in penstocks.

Step-by-step solution

1. Identify the component: Surge tank is placed between the reservoir and the turbine in a hydroelectric plant. 2. Analyze the function: It handles the 'water hammer' effect caused by sudden closure of turbine valves. 3. Evaluate options: Reducing hammering (pressure surges) is the primary hydraulic function of a surge tank.

Explanation

A surge tank is a small reservoir or tank provided at the end of a long penstock near the turbine to protect the pipeline from water hammer pressure. When the turbine load decreases and the governor closes the gates, the surge tank absorbs the excess water and its kinetic energy, preventing a sudden pressure rise (hammering) in the penstock.

Why the other options are wrong

A: It manages pressure fluctuations rather than maintaining a perfectly uniform pressure. C: Turbine vibrations are reduced by balancing and proper mounting, not by a surge tank. D: Power factor is an electrical parameter improved by capacitors or synchronous condensers, not hydraulic structures.

Shortcut

Surge tank = Pressure relief + Water hammer protection.

Common mistake

Confusing the surge tank with an air vessel (used in reciprocating pumps) or thinking it is used for power factor improvement (which is an electrical concept).