Title: Midterm Exam
Course: WIND 100WH Introduction to Wind Energy > Section: WIND 100WH Introduction to Wind Energy

Q: Wind power machines were developed throughout _____ in about 200BC.
- Prussia
- Egypt
- Germania
- Persia
A: Persia

Q: Roman windmills were developed in what century?
- 6th century A.D.
- 12th century B.C
- 3rd century A.D.
- 2nd century B.C.
A: 3rd century A.D.

Q: Wind power was used extensively to drain swampy areas to provide more farm land and also for _____.
- irrigation
- production
- electrical power
- flooding
A: irrigation

Q: Wind turbine farms began to spread throughout Europe in the _____.
- 1920s
- 1930s
- 1970s
- 1990s
A: 1970s

Q: Power plants use turbines to turn the electric generators. What medium turns these turbines?
- Air
- Water
- Nuclear rods
- Coal
A: Water

Q: From the 1800s to the 1900s, U.S. farmers used windmills extensively to _____.
- grind grain, pump water, and saw wood
- power heavy equipment, charge batteries, and grind metals
A: grind grain, pump water, and saw wood

Q: Electrical power demand has been on the increase.
- True
- False
A: True

Q: U.S. demand for electricity fluctuates from weekday to weekend and during different seasons.
- True
- False
A: True

Q: Why must any changes in the electrical power demand be anticipated by the producer (power plant) beforehand?
- So a cost analysis can be performed and to allow for maintenance
- To prevent over/under production of the heat needed for power generation
A: To prevent over/under production of the heat needed for power generation

Q: Changes in demand are due to _____.
- decreased power usage by industries, factories, businesses, and homes
- increased power usage by industries, factories, businesses, and homes
- the weather affects demand and also the daytime and nighttime hours
- All of the above
A: All of the above

Q: Some units include a solar-power system to aid the wind turbine.
- True
- False
A: True

Q: Return on Investment (ROI) is the amount of revenue expected to offset the costs of a project.
- True
- False
A: True

Q: A _____ is an energy-supply policy focused on supporting the development of new renewable power generation.
- feed-in tariff (FIT)
- production tax credit
- power output supplement
- power systems grant
A: feed-in tariff (FIT)

Q: Green energy payback calculations involve two parts. This calculation compares the money spent to the money earned by a project. This "payback" equals the money earned minus the money spent and this number should ideally be ______.   (Clue: Should it be Positive, Negative, or Even?)
- Positive
- Negative
- Even
- Odd
A: Positive

Q: A cost associated with installing a wind turbine could be money earned from production.
- True
- False
A: False

Q: A cost associated with installing a wind turbine could be installation costs and maintenance costs.
- True
- False
A: True

Q: It's important to perform environmental and ecological assessments when planning for a wind power system because of the _______.
- possible negative factors of installing wind turbines in the area
- needed road and infrastructure improvements
- blade's and tower's effect on migratory birds
- obstacles to aircraft if near airport or helipads
- unacceptable noise levels close to residential areas
- All of the above
A: All of the above

Q: Referring to the image above, P1 is ________ than P2 when the wind passes across the airfoil.
- greater
- lower
A: lower

Q: Referring to the image above, V1 is ________ than V2 when the wind passes across the airfoil.
- greater
- lower
A: greater

Q: Referring to the image above, the entire airfoil should move ________ when the wind passes across the airfoil.
- upward
- downward
A: upward

Q: If the blades are 140 feet in length and the rotor is turns once every 5 seconds, what would be the tip speed of the blades?
- 120mph
- 140mph
- 100mph
- 80mph
A: 120mph

Q: The purpose of _____ is to control how much wind the blades may “catch.”
- discarding
- air flow control
- wind knurling
- pitch control
A: pitch control

Q: There are two main types of wind turbines, the _____ and the _____.
- HAWT/VAWT
- WHAT/WVAT
- HWT/VWH
- HWEH/VHWE
A: HAWT/VAWT

Q: When dealing with a control loop, the set-point is the value the system’s actions are based around.
- True
- False
A: True

Q: In smaller applications, a mechanical system changes the pitch of the blades using springs to detect high centrifugal forces when the blade over speeds. When wind is strongest, the springs expand or contract, which allows the blades to be pitched and slow down.
- True
- False
A: True

Q: With passive pitch control, also called passive stall control, the blades are allowed to pivot on the hub.
- True
- False
A: False

Q: In active stall control, the pitch of the turbine blade is changed to a point at which airfoil activity on the blade no longer stalls in high
winds.
- True
- False
A: False

Q: The set-point and feedback signals are compared in a ___________ junction or comparator.
- summing
- timing
- comparing
- detecting
A: summing

Q: _____ control systems are capable of controlling the motion of devices in very small, linear steps.
- incremental
- sequential
- proportional
- collinear
A: collinear

Q: A blade is 26 meters in length, how many feet is this? (3.28 feet = 1 meter)
- 85.3 feet
- 16.7 feet
- 7.9 feet
- 125.5 feet
A: 85.3 feet

Q: How many 12-foot tubes are needed to make a run of 32 feet?
- 14
- 6
- 3
- 2
A: 3

Q: Some advantages of three-blade HAWTS are _________.
- low vibration
- quieter operation
- more power at lower rpm
- all of the above
A: all of the above

Q: Some disadvantages of two-bladed HAWTS are __________.
- high vibration
- quietest operation
- more power at low rpm
- all of the above
A: high vibration

Q: The enclosure at the top of the HAWT tower, which houses the generator, gearbox, shafts, bedplate, and other equipment, is called the ________.
- nacelle
- housing
- cover
- bonnet
A: nacelle

Q: Referring to the image above, what causes output zero to become active?
- When input zero is active and input one is not active
- Only when input zero is active and input one is active
- When either or both input zero and input one are active
- none of the above
A: When either or both input zero and input one are active

Q: To make output one active, what must happen?
- Output zero must be active and inputs two and three must both be active
- Output two must be active and inputs zero and three must also be active
- Input zero and input three must both be active
- None of the above
A: Output zero must be active and inputs two and three must both be active

Q: Referring to the image above - Input field devices are attached to the input card
of the PLC with the program mentioned in questions one through five. SW 1 and SW 2
are normally-open switches. PSW 1 is a normally-open pressure switch, which closes
when the pressure reaches 200PSI. TSW 1 is a normally-open temperature switch, which
closes when the temperature reaches 150 degrees Fahrenheit. Output zero is connected
to a light bulb, which lights when output zero becomes active. When active, output one
turn a motor on.

When does the indicator lamp turn on?
- when output zero is inactive
- only when both SW 1 and SW 2 switches are closed
- if PSW 1 and TSW 1 are closed
- if either or both SW 1 or SW 2 switches are closed
A: if either or both SW 1 or SW 2 switches are closed

Q: Referring to the image above - Input field devices are attached to the input card
of the PLC with the program mentioned in questions one through five. SW 1 and SW 2
are normally-open switches. PSW 1 is a normally-open pressure switch, which closes
when the pressure reaches 200PSI. TSW 1 is a normally-open temperature switch, which
closes when the temperature reaches 150 degrees Fahrenheit. Output zero is connected
to a light bulb, which lights when output zero becomes active. When active, output one
turn a motor on.

The indicator lamp illuminates when _____________.
- output zero is active
- either or both SW 1 and SW 2 switches are closed
- the second rung is now ready
- all of the above
A: all of the above

Q: Referring to the image above - Input field devices are attached to the input card
of the PLC with the program mentioned in questions one through five. SW 1 and SW 2
are normally-open switches. PSW 1 is a normally-open pressure switch, which closes
when the pressure reaches 200PSI. TSW 1 is a normally-open temperature switch, which
closes when the temperature reaches 150 degrees Fahrenheit. Output zero is connected
to a light bulb, which lights when output zero becomes active. When active, output one
turn a motor on.

Switches PSW 1 and TSW 1 are both closed, but the motor does not run. Assuming the program is correct, what corrective step/s should be taken to fix this fault?
- Ensure indicator lamp is illuminated and not faulty.
- Check that either or both SW 1 and SW 2 are closed and working properly.
- Check the PSW and TSW switches for faults and make certain they are both closed.
- All of the above
A: All of the above

Q: The above rung-logic symbol and notation indicates an internal program input, which is controlled by ______________.
- output zero
- input zero
- a timer
- It is not a practical symbol.
A: output zero

Q: Inputs two and three act as a two-input OR function.
- True
- False
A: False

Q: Referring to the image above - Input field devices are attached to the input card
of the PLC with the program mentioned in questions one through five. SW 1 and SW 2
are normally-open switches. PSW 1 is a normally-open pressure switch, which closes
when the pressure reaches 200PSI. TSW 1 is a normally-open temperature switch, which
closes when the temperature reaches 150 degrees Fahrenheit. Output zero is connected
to a light bulb, which lights when output zero becomes active. When active, output one
turn a motor on.

What conditions must be met in order for the motor to run?
- Somewhere within the system a temperature of 150 degrees Fahrenheit and pressure of 200PSI must both be met.
- Either or both switches SW 1 and SW 2 must be closed.
- All of the above
- None of the above
A: All of the above

Q: Referring to the image above - Input field devices are attached to the input card
of the PLC with the program mentioned in questions one through five. SW 1 and SW 2
are normally-open switches. PSW 1 is a normally-open pressure switch, which closes
when the pressure reaches 200PSI. TSW 1 is a normally-open temperature switch, which
closes when the temperature reaches 150 degrees Fahrenheit. Output zero is connected
to a light bulb, which lights when output zero becomes active. When active, output one
turn a motor on.

Inputs become active when they receive a proper input voltage. When activated, outputs supply a voltage for field devices.
- True
- False
A: True

Q: What type of hydraulic pump is shown above?
- Gear pump
- Lobe pump
- Vane pump
- Arc pump
A: Vane pump

Q: The images above are the internals of ______________.
- ball valves
- slip valves
- check valves
- springing ball valves
A: check valves

Q: In the image above, hydraulic piston A has a diameter of 2 inches and can travel into its cylinder a length (l_1) of 5 inches. Piston B has a diameter of 4.5 inches. If piston A is forced all the way down into its cylinder (the full 5 inches), how far does piston B move upward (i.e. find l_2)?
- About 2 inches
- Almost 1.5 inches
- Almost an inch
- A little more than a 3 inches
A: Almost an inch

Q: Referring to the previous question, if 10 pounds of force is applied to the first cylinder, how much up force would be on the
secondary cylinder?
- About 5 pounds
- A little more than 50 pounds
- A little less than 25 pounds
- The same amount: 10 pounds
A: A little more than 50 pounds

Q: Referring to the image above, what device could be used to prevent the secondary cylinder fluid from back feeding into the primary
cylinder?
- Stop valve
- Ball valve
- Check valve
- Reducer
A: Check valve

Q: The image above is an example of a/n ________________ - type hydraulic pump.
- double vane
- variable valve
- double gear
- double helix
A: double gear

Q: _________________ occurs in a cylinder when fluid enters the top and pushes the piston down.
- Displacement
- Volumetric pressure
- Transfer power
- Cooling
A: Displacement

Q: What is the name of the pump that gives out a predetermined quantity of fluid for each revolution?
- Hydraulic pump
- Low displacement hydraulic pump
- Positive displacement pump
- Negative displacement pump
A: Positive displacement pump

Q: A wind turbine rotor changes wind into a/n _____ motion and a generator changes this motion into _____ power.
- linear / dynamic
- rotating / electrical
- electrical / wind
- mechanical / mechanical
A: rotating / electrical

Q: The device that changes rotating mechanical power into electrical power is called the _____.
- electro-mechanism
- shifter
- electric battery
- electric generator
A: electric generator

Q: The acronym VAWT stands for _____.
- vertical air and wind transformation
- vertical access wind transfer
- vertical-axis wind turbine
- vertical access wind turbine
A: vertical-axis wind turbine

Q: Most wind turbines use a multispeed _____ to keep the high-speed shaft running at a near constant speed and use a/n _____ to produce electricity at exactly 60 Hz.
- gearbox / inverter
- generator / coupler
- shaft / phase timer
- differential / transformer
A: gearbox / inverter

Q: A megawatt of power is equal to how many watts?
- 100
- 700,000
- 1,000,000
- 0.000,001
A: 1,000,000

Q: Most larger wind turbines use this very important type of control system to move the nacelle, which accommodates for the change in wind direction.
- PLC control
- Pitch control
- Yaw control
- Arch control
A: Yaw control

Q: A horizontal-axis wind turbine can be setup as a/n _____ or _____ -type turbine.
- up-wind / over-wind
- upwind / downwind
- down / diagonal
- pitched over / graded up
A: upwind / downwind

Q: Keeping a wind farm on schedule and within budget is the responsibility of the _____.
- site lead
- architectural manager
- oversight crew
- project manager
A: project manager

Q: By researching wind patterns, scientists are able to predict where the wind will be the _____.
- strongest and most destructive
- most available and predictable
- most predictable and weakest
- strongest and most continuous
A: strongest and most continuous

Q: Wind near the ground is very likely to be affected by _____.
- force
- resistance
- friction
- coercion
A: friction

Q: A wind turbine that produces 1.45 KWh continuously is able to produce approximately how many KWh annually?
- 450 KWh
- 2,300 KWh
- 12,700 KWh
- 1.45 KW
A: 12,700 KWh

Q: Which of these shows the correct engineering notation for 23,200,000?

A) 23.2 x 10^6

B) 23.2 x 10-^6

C) 23.2 x 10^10

D) 23.2 x 10^5
- A
- B
- C
- D
A: A

Q: What’s it called when a blade's pitch has been changed to the point it begins to stall?
- Stall control
- Pitch control
- Furling
- Stalled pitch
A: Furling

Q: Drag on a blade is always on the ______________.
- leading edge of the blade
- trailing edge of the blade
- stall control related to the blade
- drag coefficient metering devices
A: leading edge of the blade

Q: The blade pitch angle at which wind power absorption is best is called the _____ and the blades would be considered to be at _____ pitch.
- angle of incidence / maximum
- angle of velocity / minimum
- power angle / critical
- critical angle / full
A: critical angle / full

Q: What is the cut-out speed (the maximum speed of the wind allowed before shutdown) for most large wind turbines?
- 45 mph
- 64 mph
- 33 mph
- 19 mph
A: 33 mph

Q: What’s the major problem of passive control wind turbines?
- Efficiency issues
- Too many moving parts
- Cut out wind speeds are too low
- Too many CPU systems
A: Too many moving parts

Q: Lentz’s Law helps to explain the properties of _____.
- electromagnetic induction
- core potential
- power circuits
- power coefficients
A: electromagnetic induction

Q: A commercial wind turbine has blades 120 feet in length from the center of the hub to the tips. If the turbine is turning at 20 rpm, what is the angular speed of the blade tips?
- 35.6 rpm, or 220 miles
- 1,750.78 ft/s, or 10 feet per mile an hour
- 251.3 feet per second, or 171.4 mph
- 171.4 mph, or 220 feet per hour
A: 251.3 feet per second, or 171.4 mph

Q: Yaw control systems mostly use a/n ________________, a gear reduction box, and a yaw ring gear.
- hydraulic system
- electric motor
- PLC hub system
- reluctance device
A: electric motor

Q: On larger wind turbines, what device is responsible for limiting the number of times the nacelle can rotate in one direction?
- Yaw counter
- PLC
- Inverter
- Anemometer
A: PLC

Q: Anemometers generate a _______________ to indicate wind speed, while wind vanes utilize variable resistors and indicate wind direction by _______________.
- voltage / resistance
- sine wave / power signals
- voltage / pulsing data signals
- tor / encoders
A: voltage / resistance

Q: A valve in a hydraulic system that consists of a poppet and is designed to allow flow in one direction (thus preventing backflow) is called a/n ___________.
- lobe valve
- directional valve
- check valve
- ball valve
A: check valve

Q: On a two-blade wind turbine, the counterweights perform two functions. What are they?
- Increase angular velocity and dampen noise
- Maintain torque and velocity
- Allow wobble in high winds
- Balance the shaft and also harvest the wind
A: Balance the shaft and also harvest the wind

Q: What are the two different active systems for controlling blade pitch?
- Hydraulic control and electric motor control
- Spring control and counterweight control
- Hydraulic control and pneumatic control
- Pressure control and reduction system control
A: Hydraulic control and electric motor control

Q: What’s the name of the pump that gives out a predetermined quantity of fluid per revolution?
- Hydraulic pump
- Low displacement hydraulic pump
- Positive displacement pump
- Negative displacement pump
A: Positive displacement pump