Title: Module 2 Test, Part 3
Course: WIND 100WH Introduction to Wind Energy > Section: WIND 100WH Introduction to Wind Energy

Q: It’s important for a wind turbine’s electrical power output frequency to be the same as the electrical grid’s frequency. What main component/s of the wind turbine make/s this possible?
- The PLC system alone
- The upper control cabinet’s PLC and PID system controllers and regulators
- The ac generator itself and an inverter when using a DC generator
- The accelerator and the PLC rectifier systems
A: The ac generator itself and an inverter when using a DC generator

Q: For most systems, the wind turbine rotor should turn between _____ rpm in effort to create 60 Hz most efficiently?
- 5 and 15
- 10 and 20
- 15 and 30
- 50 and 100
A: 10 and 20

Q: When helping to maintain the frequency of a wind turbine’s output voltage, the output shaft of the gearbox will rotate at a near constant __________.
- 1,600 rpm
- 1,800 rpm
- 1,700 rpm/60 Hz
- time
A: 1,800 rpm

Q: As the angle of attack is increased from zero, efficiency increases. However, after a certain angle is surpassed, it begins to decrease. The angle just before the blade’s efficiency begins to decrease is referred to as the __________.
- critical angle of attack
- zero angle of attack
- pitched angle of attack
- minimal drag position
A: critical angle of attack

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 areas of the turbine are likely to be affected first if it exceeds its maximum wind speed rating?
- Tower damage
- Damage to the mechanical assembly
- Generator damage
- None of the above
A: Damage to the mechanical assembly

Q: What device directly controls the hydraulic cylinder’s position when using a hydraulic blade pitch control system?
- Pitch sensor
- DTA
- Hydraulic amplifier
- Hydraulic latch
A: Hydraulic amplifier

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: Efficiency issues

Q: On passive control wind turbines, at the point the wind speed is unsafe, the blade’s increased angular velocity will keep it from producing higher amounts of _____. This design feature helps prevent over powering.
- Drag
- Torque
- Down lift
- Power per square inch
A: Torque

Q: What type of energy is wind?
- Electrical
- Anti-dynamic
- Kinetic
- Potential
A: Kinetic

Q: According to the Betz limit, what’s the maximum efficiency of a wind turbine?
- 68 %
- 63 %
- 59 %
- 88 %
A: 59 %

Q: By making a generator run with less drag, or by making the gears turn easier, a wind turbine would become _____ efficient.
- More
- Less
A: More

Q: Air density is a consideration when determining the peak performance of the ___________ on a wind turbine.
- PLC
- rotor assembly
- generator
- nacelle
A: rotor assembly

Q: Blade pitch control is used to adjust the blades so that they utilize as much wind as safely possible.
- True
- False
A: True

Q: A capacitor stores _____.
- electrical charge
- air
- vacuum
- space charge
A: electrical charge

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

Q: The active device that changes a DC source into an ac source is called a/n _____.
- inverter
- collector
- transformer
- rectifier
A: inverter

Q: The device that changes an ac source into a DC source is called a/n _____.
- inverter
- collector
- transformer
- rectifier
A: rectifier

Q: Electrical current can be generated by _____ a magnet across a _____.
- moving / voltage source
- moving / battery
- setting / coil of wire
- moving / coil of wire
A: moving / coil of wire

Q: Batteries create voltage by _____.
- a chemical process
- a magnetic process
A: a chemical process

Q: Frequency is the number of cycles completed in one second.
- True
- False
A: True

Q: Transformers work with ac, as they require a changing magnetic field to accomplish mutual inductance.
- True
- False
A: True

Q: U.S. household outlets are 120v ac RMS, 10Hz sources.
- True
- False
A: False

Q: If the speed (rpm) of an ac generator is increased, the frequency at its output decreases.
- True
- False
A: False

Q: A coefficient can be used as an adjustment factor to an equation or problem.
- True
- False
A: True

Q: The sine wave is used to describe the behavior of ac sources.
- True
- False
A: True

Q: What blade pitch position is required to utilize the greatest amount of the wind’s energy?

Q: In most large wind turbines, what’s the primary function of the PID?

Q: Name the control device that positions the nacelle into, or out of, the wind.

Q: What’s it called when a device has the ability to control the pitch in fine increments?

Q: When estimating how much energy is being converted by a wind turbine, what basic law of physics must be kept in mind?

Q: The amount of electrical power available from a wind turbine depends on what variables?

Q: In the electrical power availability formula, what value is cubed and what does it mean?

Q: When testing loads on a generator what devices are used?

Q: Finite-element Analysis (FEA) allows a technician to determine what?

Q: When calculating a power curve for wind speed vs. generator output, what would be a non-metric wind speed equivalent to 12 m/s?