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Multiple choice question for engineering

Set 1

1. Which of the following is an example of reciprocating pump?
a) Lobe pump
b) Barrel pump
c) Vane pump
d) Hand pump

View Answer

Answer: d [Reason:] Hand pump is the example of a reciprocating pump. Reciprocating pumps when made use inside a boiler. They are continuously run by steam from the same boiler to which the water is fed. Water is pumped by reciprocating action.

2. When is it difficult to maintain the pressure inside the boiler?
a) When steam demand is fluctuating
b) When steam demand is high
c) When steam demand is low
d) When steam demand is constant

View Answer

Answer: a [Reason:] Whenever the steam demand is fluctuating, it becomes very difficult to maintain uniform pressure. In such of these cases pressure reducing valve is made utilized by connecting to steam supply line. Function of the pressure reducing valve is to maintain constant pressure on the delivery side of the valve with the fluctuating boiler pressure.

3. How many types of steam traps are generally used in the boiler?
a) 1
b) 2
c) 3
d) 4

View Answer

Answer: b [Reason:] Two types of steam traps are generally used in the boiler. The function of steam trap is to drain off water resulting from the partial condensation of steam in the steam pipe lines and jackets without allowing the steam to escape through it.

4. Where is steam separator installed in the boiler?
a) Close to the engine
b) Close to the economizer
c) Close air preheater
d) Near to the superheater

View Answer

Answer: a [Reason:] Function of the steam separator is to separate the water particles in suspension that are carried by the steam coming from the boiler. It is always installed as close to the engine or turbine as possible on the main pipeline.

5. Which materials are used for Super heater tubes?
a) Nickel chromium
b) Alnico
c) Chromium Molybdenum
d) Magnox

View Answer

Answer: c [Reason:] Superheater is made of coils of tubes forming parallel tube circuits connected between heaters. The superheater tubes are made of high temperature strengths special alloy steels such of chromium molybdenum. The coils are heated by the heat of combustion gas during their passage from furnace to the chimney.

6. Super heaters are commonly classified into how many types?
a) 1
b) 2
c) 3
d) 4

View Answer

Answer: b [Reason:] Super heaters are commonly classified into two types: Radiant superheater and convective superheater. If superheater absorbs heat from the burning fuel through radiation than it is known as Radiant Superheater. If the superheater that receives its heat entirely from the gases through convective heat transfer is called Convective superheater.

7. How many methods of superheater temperature control are there?
a) 5
b) 8
c) 4
d) 2

View Answer

Answer: b [Reason:] There are eight methods of superheater temperature control. They are: 1) Bypassing the furnace 2) Tilting burners in the furnace 3) Auxiliary burners 4) De-superheater using water supply 5) Pre condensing control 6) Gas circulation 7) Twin furnace arrangement 8) Coil immersion in boiler drum.

8. In the method of ‘Tilting burners in the furnace’ at what degree are the burners tilted?
a) 10o
b) 15o
c) 30o
d) 45o

View Answer

Answer: c [Reason:] In this following method of a superheater temperature control burners in the furnace are tilted up or down through a range of 30o. When burners are tilted downwards much of heat is given to the water walls by the gas and the gas entering the super heater region is relatively cool.

9. What is the function of Re-heater in the boiler?
a) To get excess amount of heat
b) To make utilize of the left over water in the tubes
c) Re-super heat partly expanded steam
d) Better heating efficiency in winters

View Answer

Answer: c [Reason:] The function of Re-heater is to re-superheat the partly expanded steam from the turbine so that the steam remains dry as far as possible through the last stage of turbine. Modern plants have reheaters as well as super heaters in the same gas passage of the boiler.

10. How many types of economizers are there?
a) 6
b) 8
c) 5
d) 3

View Answer

Answer: a [Reason:] There are six types of economizers: A) Steaming B) Independent C) Non-steaming D) Integral E) Condensing F) Non-condensing.

11. Which is the most common type of economizer used in the thermal plants?
a) Steaming
b) Integral
c) Independent
d) Non-Condensing

View Answer

Answer: d [Reason:] The most common type of economizer used in thermal power plant is the Non-condensing thermal power plant. They are Heat exchanger tubes with fins around the in the form of spiral and they are located inside the duct at the exit region of the boiler.

12. Which type of economizer is used in Natural gas fired thermal plant?
a) Condensing
b) Steaming
c) Integral
d) Independent

View Answer

Answer: a [Reason:] Condensing economizers are used in natural gas fired thermal power plant. They reduced the flue gas temperature below condensation temperature as low as 25oC. They increase the boiler efficiency by 10-15%. While using the condenser the fuel should not contain sulfur.

13. Select the benefit of preheating the air?
a) Increased thermal efficiency
b) Improved oxidation
c) Controlled steam capacity
d) Decreased power consumption

View Answer

Answer: a [Reason:] Increased thermal efficiency is one of the benefits and also other benefits are 1) Improved combustion 2) Efficient use of low grade fuel 3) Saving in fuel consumption 4) Increased steam generation capacity.

14. Which type of air heater consists of a bunch of hollow leaves of sheet metal?
a) Plate air heater
b) Tubular air preheater
c) Regenerative
d) Integral

View Answer

Answer: a [Reason:] The plate type air heater consist a bunch of hollow leaves of sheet metal electrically welded and assembled in housing. The spacing between the adjustment leaves and the width of the opening of leaves are such that air and gas passages are of different widths.

15. Which type of air preheater is often preferred at thermal stations?
a) Regenerative heater
b) Tubular air heater
c) Plate air heater
d) Integral heater

View Answer

Answer: a [Reason:] In the regenerative heater same surface is alternately heated and cooled by the air and gas steams through respective operating cycles. These are often preferred in thermal station due to its compactness, accessibility and reduced weight.

Set 2

1. What is the function of boiler?
a) To burn the fuel in a confined closed system with the supply of air
b) To generate steam at varying pressure
c) To generate steam at constant pressure
d) To produce flue gases by burning fuel at a given pressure

View Answer

Answer: c [Reason:] Function of boiler is to generate steam at constant pressure as per the process requirement. The steam generated may be nearly dry saturated or superheated steam. Constant pressure in the boiler is maintained by generating the steam equal to the steam flowing out of the boiler.

2. Why single boiler unit per turbine is equipped commonly?
a) For better turbine control
b) To deduce the costs
c) For overcoming losses of power
d) To improve the efficiency

View Answer

Answer: a [Reason:] In modern power plants it is very common to use a single boiler unit per turbine. This leads to simpler piping systems and relatively easier boiler and better boiler control. And also operating is easier when the connection is made in this type.

3. What is the critical average pressure at which the single boiler unit per turbines is designed to handle?
a) 150 bar
b) 220 bar
c) 740 bar
d) 575 bar

View Answer

Answer: b [Reason:] Single boiler per unit turbines is designed to operate at average critical temperature of 220bar. If the boilers are designed to operate above or below the critical pressure, than they are known as super critical boilers are once through boilers. If the boilers are designed to operate below the critical pressure than they are known as sub critical or drum boilers.

4. How can be the plant efficiency of steam power plant is increased?
a) By using high pressure and high temperature steam
b) By equipping ash and flue gas clearance system
c) By maintaining the boiler on daily basis by cleaning the soot and combustion products
d) By using better and efficient type of fuel for combustion

View Answer

Answer: a [Reason:] The plant efficiency can be increased by using high pressure and high temperature steam. This also reduces the cost of electricity production. The development of newer materials permitted the use of higher operating pressure and temperature of the boiler.

5. Which type of boilers is preferred cost wise when the boilers are required to raise less than 30 tonnes of steam?
a) Flued boiler
b) Cornish boiler
c) Butterley boiler
d) Shell boiler

View Answer

Answer: d [Reason:] The use of shell boilers are considered to be cheaper when the boilers are required to raise less than 30 tonnes of steam per hour and at pressures 30bar. Above these limits, i.e. for high pressure and high output, water tube boilers are preferred.

6. What is the temperature at which the steam boilers are capable to withstand?
a) 200oC
b) 280oC
c) 540oC
d) 358oC

View Answer

Answer: c [Reason:] the modern high pressure boilers have steam capacities of 30 to 650 tonnes/hour and with pressure of upto 160 bar & maximum steam temperature of about 540oC. Also the furnace shape is not limited to cylindrical form; hence furnace shape can be changed to suit wide range of situations.

7. The _________ may have water circulation either by natural means due to difference in density or by external means.
a) Piping
b) Tubes
c) Furnace
d) Boiler

View Answer

Answer: d [Reason:] The boiler may have a water circulation either by natural means due to difference in density or by external means (forced circulation). All modern high pressure boiler plants use a pump to force the water to circulate through the boiler plant. The use of natural circulation is limited to the subcritical boilers.

8. What increases as steam pressure increases inside a boiler?
a) Force
b) Density
c) Rate of steam conversion
d) Viscosity

View Answer

Answer: b [Reason:] As the steam pressure increases, its density also increases while the corresponding increase in temperature causes density of water to decrease. This makes the pressure difference causing water flow to decrease.

9. What is needed to be increased to increase the heat transfer rate in the boiler?
a) Gas velocities
b) Fuel input
c) Water velocities
d) Air supply

View Answer

Answer: c [Reason:] Water velocity is required to be increased rather than gas velocities to increase the rate of heat transfer rate in the boiler, because a considerable increase in pressure is more easily produced with water than with gas. Hence, for a given output in boiler, smaller diameter tube may be used.

10. In what is water in high pressure boiler circulated through?
a) Conduits
b) Cove
c) Channel
d) Tubes

View Answer

Answer: d [Reason:] In high pressure boilers, water is circulated through the tubes. If the flow of water takes place through one continuous tube, there is a large resistance due to friction and also pressure drop will be more. If the flow is arranged through a parallel system of tubing i.e., through several sets of tubes which are arranged parallel pressure loss will be reduced. This also provides better control over the steam quality.

Set 3

1. How many types of basic organic decomposition occur in Biomass energy conversion?
a) 2
b) 3
c) 4
d) 5

View Answer

Answer: a [Reason:] There are two basic types of organic decomposition that can occur: aerobic decomposition (in the presence of oxygen) and anaerobic decomposition (In the absence of oxygen). All organic material, both animal and vegetable can be broken down by these processes.

2. Which decomposition process produces carbon dioxide and ammonia?
a) Aerobic decomposition
b) Anaerobic decomposition
c) Thermolysis
d) Thermal decomposition

View Answer

Answer: a [Reason:] Aerobic decomposition (fermentation) process produces carbon dioxide, ammonia and other small amounts of gases, heat in large quantities and a final product that can be used as a fertilizer. Aerobic decomposition is process of decomposition in presence of oxygen.

3. Which decomposition process produces Carbon dioxide and methane?
a) Aerobic decomposition
b) Anaerobic decomposition
c) Thermolysis
d) Thermal decomposition

View Answer

Answer: b [Reason:] Anaerobic decomposition will produce methane, carbon dioxide, some hydrogen and other gases in trace, very little heat and a final product with a higher nitrogen content than is produced by anaerobic fermentation process.

4. Anaerobic fermentation is how many staged process?
a) Single stage
b) Two – stage
c) 3-stage
d) 4 – stage

View Answer

Answer: b [Reason:] Anaerobic decomposition is a two stage process as specific bacteria feed on certain organic materials. In the first stage, acidic bacteria dismantle the complex organic molecules into peptides, glycerol, alcohol and other sugars. Than the second type of bacteria starts to convert these simpler compounds into methane.

5. In what PH range does anaerobic digestion occurs at best?
a) 6.8 – 8.0
b) 0 – 5.0
c) 2.3 – 4.5
d) 3.5 – 7.2

View Answer

Answer: a [Reason:] Anaerobic digestion will occur best within a PH range of 6.8 – 8.0. More acidic or basic mixtures will ferment at a lower speed. The introduction of raw material will often lower the PH (make the mixture more acidic).

6. Which amount is the ideal carbon-nitrogen ratio for the raw material into a biogas plant?
a) 30: 1
b) 20: 10
c) 5: 15
d) 1: 8

View Answer

Answer: a [Reason:] The bacteria responsible for anaerobic process require both elements, as do all living organisms, but they consume carbon roughly 30 times faster than nitrogen. Assuming all other conditions are favorable for biogas production, a carbon – nitrogen ratio of about 30: 1 is ideal for the raw material fed into a biogas plant.

7. Below which temperature the action off digesting bacteria decreases?
a) 16oC
b) 35oC
c) 28oC
d) 0oC

View Answer

Answer: a [Reason:] Anaerobic breakdown of waste occurs at temperatures lying between 0oC and 69oC, but the action of digesting bacteria will decrease sharply below 16oC. Production of gas is most rapid between 29oC and 41oC.

8. Which is the most suitable temperature for the production of methane in anaerobic fermentation?
a) 32 – 35oC
b) 18 – 26oC
c) 40 – 48oC
d) 10 – 15oC

View Answer

Answer: a [Reason:] A temperature between 32 – 35oC has proven most efficient for stable and continuous production of methane. Biogas produced outside this range will have a higher percentage of carbon dioxide and other gases than within this range.

9. Too nitrogen will cause ____________
a) Poisonous gases
b) Reduction in fertility of mixture
c) Reduction in quantity of mixture
d) Mixture to harden

View Answer

Answer: b [Reason:] Too much nitrogen will cause this to be left over at the end of digestion and reduce the quality of the fertilizer produced by biogas plant. The correct ratio of carbon to nitrogen will prevent loss of either fertilizer quality or methane content.

10. How much percentage of solid content is present in anaerobic digestion?
a) 8%
b) 2%
c) 32%
d) 50%

View Answer

Answer: a [Reason:] Anaerobic digestion of organics will proceed best if the input material consists of roughly 8% solids. In the case of fresh cow manure, this is the equivalent of dilution with roughly an equal quantity of water.

11. The central part of an anaerobic plant in an enclosed tank is known as ____________
a) Pit
b) Digester
c) Mixer
d) Feeder

View Answer

Answer: b [Reason:] The central part of an anaerobic plant in an enclosed tank is known as digester. This is an airtight filled with the organic waste, and which can be emptied of digested slurry with some means of catching the produced gas.

12. What is ADP stand for?
a) Adenosine terra phosphate
b) NADPH
c) Adenosine pyrophosphate
d) Adenosine tri-phosphate

View Answer

Answer: c [Reason:] Adenosine di-phosphate (ADP), also known as adenosine pyrophosphate (APP), is an important organic compound in metabolism and is essential to the flow of energy in living cells. ADP consists of three important structural components: a sugar backbone attached to adenine and two phosphate groups bonded to the 5 carbon atom of ribose.

13. What is C3H7O6P ?
a) Glyceraldehydes’ 3-phosphate
b) 3-bisphosphoglycerate
c) NADPH
d) Tryptophan

View Answer

Answer: a [Reason:] Glyceraldehydes’ 3-phosphate, also known as trio-phosphate and abbreviated as G3P, GALP or PGAL, is a chemical compound that occurs as an intermediate in several central metabolic pathways of all organisms. It is a phosphate ester of the 3-carbon sugar glyceraldehydes and has chemical formula C3H7O6P .

14. Product of anaerobic decomposition involves ___________
a) Methane
b) Lactic acid
c) Oxygen
d) Alcohol

View Answer

Answer: a [Reason:] A second type of bacteria in secondary stage of anaerobic fermentation starts to form methane. These methane producing bacteria are particularly influenced by the ambient conditions, which can slow or halt the process completely if they do not lie within a fairly narrow band.

15. Solid remnants of the original input material to the digesters are called ________
a) Ordure
b) Egests
c) Digestate
d) Manure

View Answer

Answer: c [Reason:] Digestate is the solid remnants of the original input material to the digesters that the microbes cannot use. It also consists of the mineralized remains of the dead bacteria from within the digesters. Digestate can come in three forms: fibrous, liquor, or a sludge-based combination of the two fractions.

Set 4

1. What is the percentage at which rated power from biogas in petrol engine can be developed?
a) 45%
b) 65%
c) 75%
d) 85%

View Answer

Answer: d [Reason:] Petrol engine can be operated on biogas after initially starting with petrol. Petrol replacement of 1005 is possible and petrol engines can develop about 85% of rated power where as diesel engine can develop full power.

2. Which engine can run on dual fuel with little engine modification?
a) Diesel engine
b) Petrol engine
c) IC engine
d) External combustion engine

View Answer

Answer: a [Reason:] Diesel engine can run on dual fuel with little engine modifications. Advancing the injection timing and entry of biogas with intake air, it can be achieved by providing a mixing chamber below the air cleaner which facilitates mixing of biogas with air before entering into the cylinder.

3. Which of the SI engine can be run on biogas?
a) Diesel engine
b) Petrol engine
c) IC engine
d) External combustion engine

View Answer

Answer: b [Reason:] Petrol engine can run on biogas, but it is required to be started with petrol in the beginning. Petrol engine can be modified for operation on biogas including provision for entry of biogas, throttling of intake air and advancing ignition timing.

4. What does CNG stands?
a) Converted natural gas
b) Compressed natural gas
c) Compressed Non-soluble gas
d) Compressed natural gasoline

View Answer

Answer: b [Reason:] Compressed natural gas (CNG) (methane stored at high pressure) is a fuel which can be used in place of gasoline (petrol), Diesel fuel and propane/LPG. CNG combustion produces fewer undesirable gases than the fuels mentioned above.

5. What is the full form of VRA?
a) Vibration resistant appliance
b) Vehicle Refueling Appliances
c) Volatile removal assembly
d) Validated requirement authority

View Answer

Answer: b [Reason:] Vehicle refueling appliance is abbreviated as VRAs. Certified natural gas compressors for refueling the vehicles are commercially available. These allow refueling at home and work. After upgrading with the above-mentioned technologies, the biogas (transformed into biomethane) can be used as vehicle fuel in adapted vehicles.

6. A device for converting substances (chemically or physically) into gas is called ______
a) Gasifies
b) Biogas plants
c) Draughts
d) Gas chambers

View Answer

Answer: a [Reason:] The word Gasification implies converting a solid or liquid into a gaseous fuel without leaving any solid carbonaceous residue. Gasifier is a equipment which can gasify a variety of biomass such as wood waste, agricultural waste like stalks, and roots of various crops. The gasifier is essentially a chemical reactor where various complex physical and chemical processes take place.

7. How many types of gasifiers are there?
a) 2
b) 3
c) 4
d) 5

View Answer

Answer: c [Reason:] There are four types of gasifiers namely: 1. Up draught or counter current gasifier. 2. Down draught or co-current gasifier. 3. Cross draught gasifier. 4. Fluidized bed gasifier.

8. Which is the oldest and simplest type of gasifier?
a) Counter current gasifier
b) Cross draught gasifier
c) Co-current gasifier
d) Fluidized bed gasifier

View Answer

Answer: a [Reason:] The oldest and simplest type of gasifier is the counter current or up draught gasifier. The major advantage of this type of gasifier are its simplicity, high charcoal burnout and internal heat exchange leading to low gas exit temperatures and high equipment efficiency.

9. Which is the gasifier that can be operated in small scale/amounts?
a) Counter current gasifier
b) Cross draught gasifier
c) Co-current gasifier
d) Fluidized bed gasifier

View Answer

Answer: b [Reason:] It is actually the advantage of this system that it is capable of handling very small amounts for operation. Installations below 10 KW can under certain conditions be economically feasible. The reason is the very simple gas cleaning train which can be employed when using this type of gasifier.

10. Which gasifier has better tar converting capacity?
a) Counter current gasifier
b) Cross draught gasifier
c) Co-current gasifier
d) Fluidized bed gasifier

View Answer

Answer: c [Reason:] A solution to the problem of tar entrainment in the gas stream has been found by designing co-current or down draught gasifiers, in which primary gasification air is introduced at or above the oxidation zone in the gasifier.

11. Which gasifier has a minimum tar converting capability?
a) Counter current gasifier
b) Cross draught gasifier
c) Co-current gasifier
d) Fluidized bed gasifier

View Answer

Answer: b [Reason:] A disadvantage of cross draught gasifiers is their minimal tar converting capacity and the consequent needs for the high quality charcoal. It is because of the uncertainty of charcoal quality that a number of charcoal gasifiers employ down draught principle, in order to maintain at least a minimal tar cracking capability.

12. Which gasifier equipment has inability to operate on a number of unprocessed fuels?
a) Counter current gasifier
b) Cross draught gasifier
c) Co-current gasifier
d) Fluidized bed gasifier

View Answer

Answer: c [Reason:] Down draught gasifier or co-current gasifiers equipment lies in its inability to operate on a number of unprocessed fuels. In particular, fluffy, low density materials give rise to flow problems and excessive pressure drop and the solid fuel must be pelletized before use.

Set 5

1. How much power does the small scale wind machine generate?
a) 18 KW
b) 2 KW
c) 12 KW
d) 30 KW

View Answer

Answer: b [Reason:] These might be used on farms remote applications and other places requiring relatively low power. The generating capacity is up to 2kW. Small scale wind machines lower your electricity bills by 50% – 90%.

2. Which type of wind machines are used at several residence or local use?
a) Large size machines
b) Remote machines
c) Small size machines
d) Medium size machines

View Answer

Answer: d [Reason:] These wind turbines may be used to supply less than 100 kW rated capacity, to several residences or local use. These do not require much space they can be installed on roof tops or on some high elevated areas.

3. Which type of wind turbines produce 100 kW or greater?
a) Large machines
b) Small machines
c) Medium machines
d) Remote Machines

View Answer

Answer: a [Reason:] Large wind turbines are those of 100 kW rated capacity or greater. They are used to generate power for distribution in central power grids. They can have single generator at a single site or multiple generators sited at several places over an area.

4. Which part of the wind mill acts as a housing for the turbine?
a) Wind Vane
b) Shaft
c) Wind mill head
d) Turbine

View Answer

Answer: c [Reason:] The wind mill head supports the rotor, housing, and rotor bearings. It also has control mechanism like changing the pitch of the blades for safety devices, tail vane to orient the rotor to face the wind. Its body is the size of the mini bus.

5. A rotor installed in a fixed orientation with the swept area perpendicular to the pre dominate wind direction is called ______
a) Nacelle
b) Yaw fixed machines
c) Blades
d) Anemometer

View Answer

Answer: b [Reason:] In the locations with the prevailing wind in one direction, the design of a turbine can be greatly simplified. The rotor can be installed in a fixed orientation with the swept area perpendicular to the pre dominate wind direction. This machine is called yaw fixed.

6. How is the action of yaw controlled in small turbines?
a) Tail vane
b) Blades
c) Shaft
d) Yaw motor

View Answer

Answer: a [Reason:] In small turbines, yaw action is controlled by a tail vane while is larger machines a servomechanism operated by a wind-direction sensor controls the yaw motor keeping the turbine properly oriented.

7. Which part of the wind turbines senses wind speed, wind direction, shaft speed and torque?
a) Turbine blade
b) Shaft
c) Rotor
d) Controller

View Answer

Answer: d [Reason:] The controller senses wind speed, wind direction, shafts speeds and torques, output power and generator temperature, Control signals are generated with the electrical output corresponding to the wind energy input.

8. Which type of wind turbine has low RPM?
a) Small wind turbine
b) Large wind turbine
c) Medium wind turbine
d) Remote wind turbine

View Answer

Answer: b [Reason:] The rate of rotation of large wind turbine generators operating at rated capacity or below is controlled by varying the pitch of the rotor blades. It has low rpm, about 40 to 50. It is necessary to increase greatly the low rotor rate of turning using transmission mechanism.

9. Why recommendation of fixed ratio gears done for top mounted equipment?
a) Because they are easy install
b) Requires less space
c) Due to its low cost
d) Because of their high efficiency

View Answer

Answer: d [Reason:] Fixed ratio gears are recommended for top mounted equipment because of their high efficiency, and minimum system risk. For bottom mounted equipment requiring a right angle drive transmission costs can be reduced on the hub by increasing rotor speed to generator.

10. Which type of generator are made use in wind turbines?
a) Recreational generators
b) Synchronous generator
c) Asynchronous generator
d) Alternator

View Answer

Answer: b [Reason:] Generators may be either constant or variable speed type. Variable speed units are expensive and/or unproved. Constant speed generator in use are synchronous induction and permanent magnet types. Synchronous unit is used for large aero generator systems. It is very versatile and has an extensive data base.

11. In which part do we find sensors and actuators?
a) Fixed gears
b) Turbines
c) Control systems
d) Blades

View Answer

Answer: c [Reason:] Control systems involves sensors and actuators. The modern large wind turbine generator requires a versatile and reliable control system. A control system is used for 1) changing the orientation of the rotor into the wind. 2) Start up and cut-in of the equipment. 3) Power control of the rotor by varying the pitch of the blades.

12. How many types of supporting tower for wind mill are generally used?
a) 2
b) 4
c) 3
d) 5

View Answer

Answer: b [Reason:] Four types of generating tower are used generally: 1) The reinforced concrete tower 2) The pole tower 3) The built up shell tube tower 4) The truss tower.

13. On what does the selection of supporting structure depends?
a) Length of blades
b) Rotating capacity
c) Capacity of generator
d) Transmission systems

View Answer

Answer: d [Reason:] The type of the supporting structure and its height is related to cost and the transmission system incorporated. Horizontal axis wind turbines are mounted on towers so as to be above the level of turbulence and other ground related effects.

14. At what type of location vibrations are more in the wind turbine?
a) Downwind location
b) Up wind location
c) Windward
d) Leeward

View Answer

Answer: b [Reason:] In the upwind location (i.e. the wind encounters the turbine before reaching the tower), the wake of the passing rotor blades causes repeated changes in the wind forces on the wind forces on the tower. Due to this the tower may vibrate and may eventually be damaged.

15. At what type of location vibrations are less in the wind turbines?
a) Windward
b) Leeward
c) Downwind location
d) Upwind Location

View Answer

Answer: c [Reason:] If the turbine is downwind from the tower, vibrations are less but the blades are subjected to severe alternating forces as they pass through the tower wake. Downwind rotors are generally preferred for large aero generators.