Hydroelectric Power Generation
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Questions and Answers

What is the main function of turbines?

  • Convert solar energy into mechanical energy
  • Convert electrical energy into mechanical energy
  • Convert mechanical energy into electrical energy
  • Convert hydraulic energy into mechanical energy (correct)

    • Which type of energy is converted into electrical energy by turbines?

  • Wind energy
  • Hydraulic energy (correct)
  • Solar energy
  • Geothermal energy

    • What is the difference between Gross Head and Net Head in turbines?

  • Gross Head is the head available at the inlet of the turbine, while Net Head is the head race level.
  • Gross Head includes all losses, while Net Head excludes losses.
  • Gross Head considers friction losses, while Net Head doesn't. (correct)
  • Gross Head is the head race level when water is flowing, while Net Head is when no water is flowing.

    • What is the formula for calculating the Net Head in a turbine?

    <p>$H - hf$</p> Signup and view all the answers

    Which of the following does NOT affect the Net Head of a turbine significantly?

    <p>Hydraulic energy input</p> Signup and view all the answers

    Why is hydroelectric power generation considered cheaper compared to oil or coal?

    <p>Hydroelectric power has lower initial setup costs</p> Signup and view all the answers

    What is defined as the ratio of power given by water to the runner of a turbine to the power supplied by the water at the inlet of the turbine?

    <p>Hydraulic Efficiency</p> Signup and view all the answers

    Which efficiency is defined as the ratio of power at the shaft of the turbine to the power delivered by water to the runner?

    <p>Mechanical Efficiency</p> Signup and view all the answers

    What is the ratio of the volume of water actually striking the runner to the volume of water supplied to the turbine called?

    <p>Volumetric Efficiency</p> Signup and view all the answers

    If a turbine is classified based on the direction of flow through the vanes, which classification does it fall under?

    <p>Radial flow turbine</p> Signup and view all the answers

    In an impulse turbine, what type of energy is available at the inlet?

    <p>Kinetic energy only</p> Signup and view all the answers

    What does the mechanical efficiency of a turbine signify?

    <p>Power delivered by water to the runner compared to power available at the shaft</p> Signup and view all the answers

    Which specific speed category do Low specific speed turbines fall under?

    <p>Low head turbine</p> Signup and view all the answers

    What happens to the power as water flows over the vanes in terms of hydraulic efficiency?

    <p>Decreases</p> Signup and view all the answers

    Which part of a turbine has power going on decreasing due to hydraulic losses as water flows over the vanes?

    <p>Runner of a turbine</p> Signup and view all the answers

    What is defined as the ratio of power available at the shaft of the turbine to the power supplied by the water at the inlet of the turbine?

    <p>Overall Efficiency</p> Signup and view all the answers

    What is the diameter of the jet in the design of a Pelton wheel?

    <p>5 times the diameter of the wheel</p> Signup and view all the answers

    In a Francis Turbine, what is the ratio of the width of the wheel to its diameter?

    <p>0.10 to 0.40</p> Signup and view all the answers

    Which turbine is suitable for a large quantity of water at low head?

    <p>Kaplan Turbine</p> Signup and view all the answers

    What is the purpose of a draft tube in a turbine system?

    <p>To discharge water from the turbine outlet to the tail race</p> Signup and view all the answers

    What is the flow ratio for a Francis Turbine?

    <p>0.15 to 0.30</p> Signup and view all the answers

    What does a Kaplan Turbine utilize for energy conversion?

    <p>Both pressure and kinetic energy</p> Signup and view all the answers

    In what direction does water enter the runner of a modern Francis Turbine?

    <p>Radial direction</p> Signup and view all the answers

    What does 'hub' or 'boss' refer to in an axial flow reaction turbine?

    <p>'Hub' acts as a runner for axial flow turbine</p> Signup and view all the answers

    'Vi' refers to what in a Francis Turbine?

    <p>'Vi' velocity of whirl at outlet</p> Signup and view all the answers

    What happens to the position of the fly-balls in the centrifugal governor when the turbine speed increases beyond normal?

    <p>Move upward due to increased centrifugal force</p> Signup and view all the answers

    How does the control valve respond to the movement of the sleeve in the system?

    <p>Piston rod moves downward, closing valve V and opening valve V1</p> Signup and view all the answers

    What is the purpose of decreasing the area of flow of water at the outlet of the nozzle in the relay cylinder?

    <p>To reduce the rate of flow of water to the turbine</p> Signup and view all the answers

    What happens when the speed of the turbine becomes normal after a decrease in generator load?

    <p>The fly-balls return to their normal position</p> Signup and view all the answers

    Why does the oil under pressure from the control valve move through valve V to the servomotor?

    <p>To exert force on face A of the piston in the relay cylinder</p> Signup and view all the answers

    What is the role of the horizontal lever supported over a fulcrum in the system?

    <p>Connects sleeve and piston rod of control valve</p> Signup and view all the answers

    What type of turbine is known as axial flow turbine?

    <p>Radial flow turbine</p> Signup and view all the answers

    Which part of the Pelton wheel controls the amount of water striking the buckets?

    <p>Nozzle and flow regulating arrangement (spear)</p> Signup and view all the answers

    What is the purpose of the casing in a Pelton turbine?

    <p>To prevent splashing and discharge water to tail race</p> Signup and view all the answers

    What material are the buckets of a Pelton wheel typically made of?

    <p>Cast iron, cast steel, bronze, or stainless steel</p> Signup and view all the answers

    Which turbine is named after L.A. Pelton, an American Engineer?

    <p>Pelton wheel or Pelton turbine</p> Signup and view all the answers

    What happens when the spear in the nozzle of a Pelton wheel is pushed forward?

    <p>Water flow decreases</p> Signup and view all the answers

    What is the function of the breaking jet in a Pelton turbine?

    <p>To stop the runner in a short time</p> Signup and view all the answers

    What is the shape of the buckets in a Pelton wheel?

    <p>Double hemispherical cup or bowl</p> Signup and view all the answers

    What does the splitter do in a Pelton wheel bucket?

    <p>Divide the jet into two equal parts</p> Signup and view all the answers

    What direction does water flow through a radial flow turbine?

    <p>From outwards to inwards radially</p> Signup and view all the answers

    What is the purpose of using a draft-tube in a reaction turbine?

    <p>To convert kinetic energy into useful pressure energy</p> Signup and view all the answers

    Without a draft-tube, where does the kinetic energy rejected at the outlet of the turbine go?

    <p>It goes to waste into the tail race</p> Signup and view all the answers

    What is the main purpose of governing a turbine?

    <p>To regulate the rate of flow through the turbine</p> Signup and view all the answers

    How is governing of a turbine achieved?

    <p>Automatically using a governor</p> Signup and view all the answers

    What is the role of an oil pressure governor in governing a Pelton turbine?

    <p>Regulating the rate of flow through the turbine</p> Signup and view all the answers

    What happens to the speed of a generator when there is a decrease in load?

    <p>It increases beyond normal speed</p> Signup and view all the answers

    Which type of draft-tube requires less space compared to others?

    <p>Simple elbow tubes</p> Signup and view all the answers

    What is true about turbines directly coupled to electric generators?

    <p>They require governing to maintain constant speed under all conditions</p> Signup and view all the answers

    Why does a reaction turbine fitted with a draft-tube have increased efficiency?

    <p>As it converts kinetic energy into useful pressure energy</p> Signup and view all the answers

    What is the role of a gear pump in governing a Pelton turbine?

    <p>Regulating flow through the turbine by oil pressure</p> Signup and view all the answers

    What is the main purpose of turbines?

    <p>Converting hydraulic energy into mechanical energy</p> Signup and view all the answers

    What is the difference between Gross Head and Net Head in a turbine?

    <p>Gross Head is the total head available; Net Head accounts for losses such as friction</p> Signup and view all the answers

    What does the mechanical efficiency of a turbine signify?

    <p>Ratio of useful power output to total energy input</p> Signup and view all the answers

    Why is hydroelectric power generation considered cheaper compared to oil or coal?

    <p>Hydroelectric power utilizes a free source of energy, water</p> Signup and view all the answers

    What is the formula for calculating the Net Head in a turbine?

    <p>$H = Hg - hf$</p> Signup and view all the answers

    Which efficiency of a turbine signifies the ratio of power delivered by water to the runner to the power available at the shaft?

    <p><strong>Hydraulic Efficiency</strong></p> Signup and view all the answers

    What is the purpose of the draft-tube in a turbine system?

    <p>To establish a negative head at the runner outlet</p> Signup and view all the answers

    In the design of a Pelton wheel, what is the diameter of the jet?

    <p>$5d$</p> Signup and view all the answers

    What is the type of turbine that has water flowing parallel to the axis of shaft rotation?

    <p>Axial Flow Turbine</p> Signup and view all the answers

    For a Kaplan Turbine, what distinguishes it from a propeller turbine?

    <p>Adjustability of vanes</p> Signup and view all the answers

    What defines the hydraulic efficiency for a Francis Turbine?

    <p>$Vw1u1/gH$</p> Signup and view all the answers

    In the design of a Pelton wheel, what is the depth of the buckets?

    <p>$1.2d$</p> Signup and view all the answers

    What does the flow ratio represent in Francis Turbines?

    <p>$Vf1/SQ ROOT of 2gH$</p> Signup and view all the answers

    What characterizes an inward flow reaction turbine like the Francis Turbine?

    <p>$Vi = 0$ at outlet</p> Signup and view all the answers

    What is the speed ratio for a Francis Turbine?

    <p>$0.6 to 0.9$</p> Signup and view all the answers

    For an axial flow reaction turbine, what part acts as the runner?

    <p>'hub' or 'boss'</p> Signup and view all the answers

    What type of turbine is a Pelton wheel or Pelton turbine?

    <p>Tangential flow impulse turbine</p> Signup and view all the answers

    Which part of the Pelton turbine helps to prevent splashing of water and discharge water to the tail race?

    <p>Casing</p> Signup and view all the answers

    What is the purpose of the breaking jet in a Pelton turbine?

    <p>To stop the runner quickly</p> Signup and view all the answers

    What material are the buckets of a Pelton wheel typically made from?

    <p>Cast steel or bronze</p> Signup and view all the answers

    What allows the jet of water in a Pelton wheel to get deflected through 160° or 170°?

    <p>Splitter shape</p> Signup and view all the answers

    What happens when the spear in the nozzle of a Pelton wheel is pushed back?

    <p>Water striking the runner increases</p> Signup and view all the answers

    Which part of a Pelton turbine does not perform any hydraulic function?

    <p>Casing</p> Signup and view all the answers

    What is provided to control the amount of water striking the runner in a Pelton turbine nozzle?

    <p>Spear</p> Signup and view all the answers

    Which part of a Pelton wheel divides the jet of water into two equal parts?

    <p>Splitter</p> Signup and view all the answers

    What kind of flow does a Pelton turbine utilize?

    <p>Tangential flow impulse</p> Signup and view all the answers

    What happens to the speed of the generator when the load on the generator decreases?

    <p>The speed of the generator increases.</p> Signup and view all the answers

    What is the formula for calculating Hydraulic Efficiency?

    <p>Power delivered to runner / Power supplied at inlet</p> Signup and view all the answers

    What effect does the movement of the fly-balls in the centrifugal governor have on the sleeve?

    <p>The sleeve moves upward.</p> Signup and view all the answers

    What does Mechanical Efficiency represent in a turbine system?

    <p>The power at the shaft of the turbine in relation to power delivered by water to the runner</p> Signup and view all the answers

    Which turbine classification is based on the direction of flow through the runner?

    <p>Radial flow turbine</p> Signup and view all the answers

    How does the control valve respond when the sleeve in the system moves downward?

    <p>The control valve opens.</p> Signup and view all the answers

    What is the immediate effect of opening valve V, in the relay cylinder system?

    <p>Increase in water flow to the turbine.</p> Signup and view all the answers

    What does Volumetric Efficiency measure in a turbine?

    <p>The volume of water actually striking the runner in relation to volume supplied</p> Signup and view all the answers

    Why does the lever turn about the fulcrum when the sleeve moves in the system?

    <p>To close valve V</p> Signup and view all the answers

    How is Overall Efficiency defined in a turbine system?

    <p>Ratio of power available at the shaft to power supplied at the inlet</p> Signup and view all the answers

    In a reaction turbine, what happens to pressure energy as water flows through the runner?

    <p>Pressure energy decreases as kinetic energy increases</p> Signup and view all the answers

    What is the primary role of the centrifugal governor in this turbine system?

    <p>To control generator speed</p> Signup and view all the answers

    What differentiates Impulse and Reaction turbines based on energy at the inlet?

    <p>'Impulse turbines have only kinetic energy; Reaction turbines have kinetic and pressure energy.'</p> Signup and view all the answers

    'Hub' or 'boss' in an axial flow reaction turbine refers to what component?

    <p>'The rotating part with fixed vanes'</p> Signup and view all the answers

    What specific speed category do Medium specific speed turbines fall under?

    <p>Medium specific speed turbine</p> Signup and view all the answers

    What is the purpose of a draft-tube in a reaction turbine?

    <p>To convert kinetic energy into useful pressure energy</p> Signup and view all the answers

    What is the governing of a turbine defined as?

    <p>Keeping the speed of the turbine constant under varying load conditions</p> Signup and view all the answers

    Which type of draft-tube is considered most efficient?

    <p>Conical draft-tubes</p> Signup and view all the answers

    What is the role of a gear pump in governing a Pelton turbine?

    <p>Ensures proper oil pressure for governing operations</p> Signup and view all the answers

    Why is governing of a turbine necessary when it is directly coupled to an electric generator?

    <p>To keep the speed of the generator constant under fluctuating load conditions</p> Signup and view all the answers

    What does governing of a Pelton turbine involve?

    <p>Maintaining constant turbine speed with changing loads</p> Signup and view all the answers

    What happens to the pressure at the outlet of the runner in a reaction turbine without a draft-tube?

    <p>It remains equal to atmospheric pressure</p> Signup and view all the answers

    What is the main function of turbines in a hydroelectric power plant?

    <p>To generate electrical energy efficiently</p> Signup and view all the answers

    What type of turbine is suitable for large quantities of water at low head?

    <p>Kaplan Turbine</p> Signup and view all the answers

    Which part of a Pelton turbine controls the amount of water striking the buckets?

    <p>Nozzle needle or spear rod</p> Signup and view all the answers

    What is the primary function of turbines in a hydroelectric power plant?

    <p>Convert hydraulic energy into mechanical energy</p> Signup and view all the answers

    In a turbine system, what is the Gross Head defined as?

    <p>Difference between head race level and tail race level with no water flowing</p> Signup and view all the answers

    What is the Net Head in a turbine system primarily affected by?

    <p>Head loss due to friction between penstocks and water</p> Signup and view all the answers

    Which efficiency of a turbine signifies the ratio of power delivered by water to the runner to the power available at the shaft?

    <p>Hydraulic Efficiency</p> Signup and view all the answers

    What is the formula for calculating the Net Head in a turbine system?

    <p>$H = H_g - h_f$</p> Signup and view all the answers

    Which part of a Pelton turbine is responsible for controlling the amount of water striking the buckets?

    <p>Splitter</p> Signup and view all the answers

    What happens to the speed of the turbine when the load on the generator decreases?

    <p>It increases</p> Signup and view all the answers

    How does the centrifugal governor respond to an increase in turbine speed?

    <p>The fly-balls move upward</p> Signup and view all the answers

    What is the role of the oil pressure governor in controlling the turbine speed?

    <p>Maintains turbine speed</p> Signup and view all the answers

    How does the movement of the fly-balls in the centrifugal governor impact the control valve?

    <p>Opens valve V</p> Signup and view all the answers

    What effect does increasing the rate of flow of water to the turbine have on turbine speed?

    <p>Increases turbine speed</p> Signup and view all the answers

    How does a decrease in generator load affect the rate of flow of water to the turbine?

    <p>Decreases flow rate</p> Signup and view all the answers

    What is the mathematical representation of Hydraulic Efficiency?

    <p>Power delivered to the runner / Power supplied at the inlet</p> Signup and view all the answers

    What does Volumetric Efficiency represent?

    <p>Volume of water actually striking the runner to volume of water supplied to the turbine</p> Signup and view all the answers

    What classification is based on the direction of flow through the vanes of a turbine?

    <p>Runner direction classification</p> Signup and view all the answers

    Which type of turbine has the water completely enclosed in an air-tight casing?

    <p>Reaction turbine</p> Signup and view all the answers

    What is the role of Overall Efficiency in a turbine system?

    <p>To evaluate total efficiency</p> Signup and view all the answers

    Which parameter does Mechanical Efficiency measure in a turbine system?

    <p>Power available at the shaft</p> Signup and view all the answers

    What distinguishes High Head, Medium Head, and Low Head turbines?

    <p>Head classification</p> Signup and view all the answers

    How are hydraulic losses primarily incurred in a turbine system?

    <p>Due to non-smooth vanes</p> Signup and view all the answers

    Which part of a turbine system has slightly less volume of water striking it than supplied?

    <p>Runner</p> Signup and view all the answers

    What differentiates Impulse and Reaction turbines based on energy transfer?

    <p>Kinetic energy throughout for Impulse, pressure energy conversion for Reaction</p> Signup and view all the answers

    What is the function of the draft tube in a turbine system?

    <p>To guide the flow of water from the runner to the tail race</p> Signup and view all the answers

    What characterizes a Francis Turbine in terms of water discharge at the outlet?

    <p>Radial discharge</p> Signup and view all the answers

    What is the main purpose of a splitter in a Pelton wheel design?

    <p>To divide the water jet</p> Signup and view all the answers

    What is the ratio called that represents the width of the wheel compared to its diameter in Francis Turbines?

    <p>N ratio</p> Signup and view all the answers

    In a Kaplan Turbine, what differentiates it from a Propeller Turbine?

    <p>The adjustability of vanes</p> Signup and view all the answers

    What is the design flow ratio for Francis Turbines?

    <p>$Vf1/SQ ROOT of 2gH$</p> Signup and view all the answers

    What does the speed ratio represent in Francis Turbines?

    <p>Ratio of speed at inlet to square root of 2gH</p> Signup and view all the answers

    In an Axial Flow Reaction Turbine, what does the hub act as?

    <p>Runner for the turbine</p> Signup and view all the answers

    What is the significance of zero whirl velocity at the outlet (Vi) in a Francis Turbine?

    <p>Indicates radial discharge at outlet</p> Signup and view all the answers

    What type of turbine is a Pelton wheel?

    <p>Axial flow turbine</p> Signup and view all the answers

    Which part of a Pelton turbine controls the amount of water striking the buckets?

    <p>Nozzle and flow regulating arrangement</p> Signup and view all the answers

    What does the spear in the nozzle of a Pelton wheel control?

    <p>Amount of water striking the runner</p> Signup and view all the answers

    What material are the buckets of a Pelton wheel primarily made of?

    <p>Stainless steel</p> Signup and view all the answers

    What is the function of a breaking jet in a Pelton turbine?

    <p>Stop the runner quickly</p> Signup and view all the answers

    What is the primary purpose of the casing in a Pelton turbine?

    <p>Prevent water splashing and discharge to tail race</p> Signup and view all the answers

    What is the specific classification of a turbine where water flows from inwards to outwards radially?

    <p>Outward radial flow turbine</p> Signup and view all the answers

    What happens when a spear in the nozzle of a Pelton wheel is pushed forward?

    <p>Reduces the amount of water striking the runner</p> Signup and view all the answers

    What part of a Pelton wheel does NOT perform any hydraulic function?

    <p>Casing</p> Signup and view all the answers

    What does a splitter do in a Pelton wheel bucket?

    <p>Splits the jet into two parts</p> Signup and view all the answers

    What is the purpose of a draft-tube in a reaction turbine system?

    <p>Increases the efficiency of the turbine</p> Signup and view all the answers

    How does the use of a draft-tube impact the net head on a reaction turbine?

    <p>Increases the net head on the turbine</p> Signup and view all the answers

    Which type of draft-tube is considered most efficient among the commonly used ones?

    <p>Conical draft-tubes</p> Signup and view all the answers

    What is the governing of a turbine defined as?

    <p>Regulating the rate of flow through the turbines according to changing load conditions</p> Signup and view all the answers

    Why is governing of a turbine necessary in hydroelectric power plants?

    <p>To maintain constant speed of the generator under varying load conditions</p> Signup and view all the answers

    How is governing of a Pelton turbine typically achieved?

    <p>By adjusting oil pressure using a governor system</p> Signup and view all the answers

    What part of a Pelton turbine plays a key role in governing by controlling water flow?

    <p>The control valve or distribution valve</p> Signup and view all the answers

    Which scenario describes what happens when governing adjusts due to decreasing load on a hydroelectric generator?

    <p>The speed of both generator and turbine increase</p> Signup and view all the answers

    What part is responsible for driving the gear pump in governing a Pelton turbine?

    <p>The power obtained from turbine shaft</p> Signup and view all the answers

    In hydroelectric power generation, why is maintaining constant speed of the generator important?

    <p>To ensure power generation is at optimal levels</p> Signup and view all the answers

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