A
- Abrasion - Wear in machinery between components grinding against each other
- Active yaw - Having controlled yaw motion rather than forced motion through wind
- Aerodynamic Force - Force exerted by moving air or gas
- Airfoil - Profile of the outline of an airplane wing, usually having large lift coefficient and a small drag coefficient
- Alignment - Having the axes in a straight line
- AC - Alternating Current, type of electricity with continuously alternating direction
- Alternator - machine generating AC electricity
- Amplitude - instantaneous value of cyclic variable
- Anemometer - windspeed measuring device
- Angular speed - rotational speed of an object in radians/sec or degrees/sec
- ANSI - American National Standards Institute
- Arc Flash - flow of electricity outside a conductor caused by a short circuit, generates high pressure and temperature in the air
- Arm - Part of a planetary gear that holds the planet gears together
- Armature - Rotating part in a motor, composed of one or more windings
- ASME - American Society of Mechanical Engineers
- Asynchronous Generator - aka induction generator
- Autotransformer - transformer where primary and secondary windings are part of the same winding, not isolated
- AWEA - American Wind Energy Association
B
- Backlash - free motion between two meshing gears due to noncontact free space between teeth
- Balanced Load - When three loads in a three-phase electrical system have equal values
- Bedplate - A main structure in a nacelle where all the components are mounted or attached
- Betz Limit - Maximum value of a wind turbine's power coefficient. 16/27 or 0.59
- Bevel Gear - Gears with perpendicular axes
- Blade Pitch Control - The capability of turning a turbine blade about its axis with respect to its hub
- Blade Root - attachement of blade to hub
- Blade Tip - free end tip of blade
- Bridge Rectifier - full rectifier where two sets of diodes alternatively conduct, converts AC to DC
- Brush - part of carbon in an electric machine that slides on a conductor to allow for electricity transfer between moving components to stationary components
C
- Cable Grip - Metallic device for turbine climbing
- Capacitive Reactance - Apparent resistance due to a capacitor
- Carabiner - Metallic device allowing connection of two rings in climbing equipment
- Carrier - Part of a planetary gear holding gears together called arm
- Cavitation - An interaction between metallic rotating piece and a liquid in a gearbox or pump causing erosion
- Centrifugal force - Outward force due to rotating reference frame
- Characteristic Curve - Curve exhibiting the main features of a device machine or equipment based on a major parameter
- Characteristic Diagram - aka Characteristic Curve
- Chord - Distance between leading and trailing edge of airfoil
- Chord Line - line connecting leading and trailing edge of an airfoil
- Collector - Point where turbine outputs in a windfarm are connected before being sent to grid
- Compound Interest - Periodically increased interest
- Cone Angle - angle that blades of a wind turbine make with plane perpendicular to axis of rotation
- Corrective Maintenance - fix components after it breaks rather than preventative
- Cost of Capital - Money spend to generate capital for investment
- Crowbar - Set of resistors that come into operation when generator disconnects and load vanishes, prevents overspeed
- Current - Intensity of flow of electrons in Amperes
- Line Current - Current in supply lines of three-phase electrical system
- Current Direction - Direction of electrons in a current
- Cut-in Speed - minimum speed for a turbine to generate power
- Cut-out Speed - maximum speed for a turbine to generate power
D
- Darrieus Turbine - Vertical axis wind turbine looks like eggbeater
- Delta Connection - Connects three wires of three phase electricity to a load in a triangular formation
- DFIG - Doubly fed induction generator where the rotor is made of windings and requires slip rings to connect to electricity
- Diode - Semiconductor with two terminals, allows one way curent
- DC - Direct Current type of electricity that flows in one direction
- Direct Drive Mode - Connecting a turbine and generator without a gearbox
- Discout Rate - economic term implies rate for borrowing money
- Dispatch System - communication system where all participants are informed
- Distribute Generation System - Electrical system with more than one generator, typically referring to many small sets of generators as opposed to centralized larger ones
- Downwind Turbine - Turbine where wind hits tower before blades
- Drive Gear - transfers energy to mating gear
- Drag - component of aerodynamic force parallel to wind that slows down movement
- Drag Coefficient - ratio of drag force to aerodynamic force causing it
- Drag-Type Turbine - turbine based on drag forces
- Drive Train - set of gears to obtain desired gear ratio
- Dynamo - Direct Current Generator
E
- Efficiency - Ratio of output energy to input energy
- Electric Circuit - setup of electrical components powered by a source
- Electric Load - consumer of electricity
- resistive - load that has only resistance
- capacitive - load consists of capacitors
- inductive - contains windings
- Electric Source - battery or generator providing power to a system
- Electromagnet - magnet made of coil and ferromagnetic core, requires electric power for magnetism
- Electromechanical System - Device with both moving and electric parts
- Energy - Potential to do work, or force applied over a distance
- Epicyclic Gear - Planetary Gear
- EWEA - European Wind Energy Association
F
- Fall Arrest - Stopping a fall from a height
- Fatigue - repeated tension/compression stress
- Fatigue Failure - failure of component due to fatigue
- Feathered - Position of wind turbine blades with smalles lift and largest drag
- Ferrous - Iron family of metals
- Fixed Speed Mode - Turbine speed constant operation
- Flashing - repeated reflection of sunshine on a turbine blade
- Flicker - Short time voltage variation in power line due to disconnect of large load
- Flickering - Shadowing effect of rotating blade
- Flutter - Vibration of wind turbine blade about its own axis
- Foundation - Massive block of concrete anchoring a tower
- Free Wheel - Standby state of wind turbine where there is insufficient wind to turn turbine
- Frequency - Number of repetitions in one second of cyclic phenomenon
- Frequency Converter - Device that changes frequency of AC
- Full-Wave Rectifier - 2 rectifier diodes that converts the entire cycle of AC to DC
- Fuse - Protection device in electrical circuit that melts to open a circuit in the case of overheat
- Future Value - value of money at future time
G
- Gearbox - mechanical device in an enclosure, converts rotational speed
- Gear - single part of gear system, gearbox component
- Arm - part of planetary gear that holds the planetary gears together
- Bevel - perpendicular axes connected gear
- Driven Gear - receives energy from mating gear
- Driving Gear - gives energy to mating Gear
- Epicyclic Gear - Planetary Gear
- Helical Gear - teeth are angled with respect to shaft axis to reduce backlash
- Idler Gear - gear that stands in between two main gears to change direction of rotation
- Internal Gear - gear in the form of ring with teeth on the inside
- Planetary Gear - set of gears arranged in form consisting of sun gear in the middle, usually 3 planetary gears engaging with sun gear and outer ring gear with internal teeth, can accept two input speeds, mounted on bracket that can turn independently
- Ring Gear - outermost gear with internal teeth in planetary gear
- Spur Gear - gear with teeth parallel to axis of rotation
- Sun Gear - innermost planetary gear
- Worm gear - gear with high ratio to reduce speed, axes set at 90 degrees
- Gear Ratio - ratio between output and input speeds in a set of gears
- Gear train - set of gears arranged to obtain a specific gear ratio
- Generator - machine that produces electricity, mechanical to electrical
- Armature - windings on the rotating part in a generator or motor, current carrying windings on a moving part
- Brush - electrical connector made of carbon or carbon composite, when electrical connection between rotating and stationary parts needed, slides on metallic rotating ring
- Rotor - rotating part of generator
- Stator - stationary part
- Grid - Electric Network
H
- Half-wave Rectifier - Simplest type of AC to DC rectifier one diode only accounts for half the wave transferred into DC
- Harmonics - frequencies that are multiples of the fundamental frequency
- Harness - part of the protective equipment or catching the wind energy by a turbine
- HAWT - Horizontal Axis Wind Turbine
- Hertz - frequency unit
- High-Speed Shaft - Output shaft in a wind turbine linked to generator shaft
- HVDC - High Voltage Direct Current transmit electricity around 300 kV DC
- Hub - part of propeller type wind turbine to connect blades
I
- Ideal Transformer - Assumed transformer with zero loss
- IEEE - Institute of Electrical and Electronics Engineers
- Induction Generator - AC generator where rotor current is generated by induction than connection to electricity as in the synchronous generator
- Inductive Reactance - Apparent resistance due to an inductor
- Inertial Force - force required for acceleration or deceleration
- Infrasound - sound with frequency below human hearing sometimes generated by wind turbines
- Initial Cost - startup costs of a project
- Inverter - converts DC to AC electricity
- Islanding - isolation of a part of AC Network from rest resulting in frequency and voltage drift
- ISO - International Standards Organization
- Isolation Transformer - Transformer used to separate a circuit from the main device
K
- Kilowatt - a thousand watts
- Kilowatt-hour - measures energy consumption
- Kinetic energy - energy associated with motion
L
- Lagging - current waveform behind the voltage waveform
- Lanyard - part of safety equipment hooked to a safe point for fall arrest, contains spring piece
- Lattice Tower - tower made from small pieces welded together into a truss
- Leading - current waveform in front of voltage waveform
- Lift - perpendicular aerodynamic force to direction of wind caused by pressure differential over an object
- Lift Coefficient - ratio of lift force to aerodynamic force causing it
- Lift-Type Turbine - turbine based on lift instead of drag
- Lockout - locking a dangerous device from normal use
- Lorentz Force - Force exerted on wire carrying a current inside Magnetic Field
M
- Main Shaft - low speed shaft in gearbox connected to rotor
- Maintenance - keeping a machine in operation
- corrective - repair after failures occur
- preventative - systematic repair regardless of state of machine
- scheduled maintenance - regular planned repair
- Met Tower - Meteorological Tower
- Motor - converts electrical energy to mechanical
N
- Nacelle - A room at the top of a turbine tower that houses gearbox, generator and other equipment
- Natural Frequency - frequency inherent to object that can resonate
- Net Present Value - economic term represents current revenues minus the total cost over lifetime of project
O
- Offshore - on a lake or sea
- Onshore - on land
- Operating Costs - continuous expenses necessary to run endeavor, such as rent, purchase of raw materials, maintenance
- Operating Speed - speed at which machine normally works
- OSHA - Occupational Safety and Health Agency
- Output - Product or result of a machine
- Overspeed - Speed above entire capacity potentially dangerous to machine
P
- Pad Mount - transformer mounted on flat surface
- Peak Hours - Electricity consumption peak hours
- Permanent Magnet - Magnet that is continuous without electrical input
- PPE - Personal Protective Equipment
- Phase Angle - angle between voltage and current waveform, time delay
- Phase Current - Current passing through a load between each of two lines in 3 phase system
- Phase voltage - voltage across each individual load in 3 phase system
- Pinion - smaller gear in a pair of gears or the output gear in drive train
- Pitch Angle - angle blade forms in reference to rotation about its axis, alters angle of attack
- Pitch Circle - represent gears size
- Pitch Control - action of controlling pitch angle of blades
- Pole Mount - transformer mounted at top of electricity distribution post
- Power - Work done in 1 second
- Active - Power converted to heat or work
- Reactive - power due to capacitor or inductor storage in one part of cycle given back in next part of cycle
- Apparent - power generator supplies for consumption
- Coefficient - in wind turbine must be less than Betz Limit ratio of electrical generation to what is in the wind
- Curve - Operational expected power curve
- Factor - ratio of active power to apparent power, smaller than 1
- Factor Correction - improving the power factor of AC currents using capacitors
- Plant - industrial unit for generation
- quality - degree of agreement to expected stability requirement, 50 or 60 Hz
- PPE - Personal Protection Equipment
- Present Value of Money - value of money expressed for a future time in today's money
- Prevailing Wind - Most common wind direction for an area
- Prime Mover - Source of mechanical power turns a generator
- Propeller Turbine - Turbine with blades similar to propeller, most common type of wind turbine
R
- Rectifier - converts AC to DC
- Renewable Energy - Energy from natural sources that is recoverable
- Reluctance Force - Force by an electromagnet trying to shorten path of magnetic field
- Ripple - Rapid fluctuations of voltage about nominal value in DC
- Root of a Blade - end of blade attaching to hub
- Rotating Magnetic Field - Magnetic field rotates about an axis, exists inside the stator of AC motors, basis of their operation
S
- Savonious Rotor - drag type turbine that consists of two half cylinders
- Scuffing - transfer of metal particles by tearing and adhesion from one tooth in a gear to another by welding
- Shadow Flicker - Moving shadow cast by rotating blade
- Shear Stress - stress due to a cutting force
- Sine Wave - Sinusoidal wave function
- Single - Phase - simplest AC electricity transmitted by 2 wires
- Skew Wind - Wind whose direction is very far off from horizontal
- Slip - act of not rotating at synchronous speed in induction motors and generators
- Slip Ring - metallic ring on rotor of certain types of AC machines to transfer electric current
- Slip Speed - difference between actual rotating speed and synchronous speed
- Smart Grid - grid equipped with automated self correcting devices
- Solidity - percentage of solid area traced in a circular rotor motion, blade area to total area
- Spar Platform - platform in the form of a vertical cylinder top for wind turbine
- Squirrel-Cage Motor - induction motor without windings, consists of bars connected by two rings, cage like structure
- Stall - decrease in lift force until drag takes over
- Control - use of stall to regulate motion of turbine
- Star connection - connect wires in a y shape as opposed to a triangular shape
- Step-down - lowering voltage
- Step-up - increasing voltage
- Substation - electrical utility to regulate electricity before sending to grid
- Synchronous Generator - AC generator with one or more magnets, electricity generated in stator when rotor rotates at a fixed frequency
- Synchronous Motor - AC motor where one or more magnets is within a rotating magnetic field causing rotor to follow the field, runs at multiples of synchronous speed
- Synchronous Speed - constant speed of electrical machine dependent on frequency of supply
T
- Tagout - put note on device or location as safety precaution
- Tension Leg Platform - floating platform kept in place by cables attached to seabed under tension
- Three-Phase System - requires 3 wires at least, each with fixed delay between them in voltage
- Thyristor - control transistor used in rectifiers and inverters
- Tip Speed - speed of tip of blade
- Ratio - ratio of tip speed to wind speed
- Torque - turning effort about a point perpendicular to rotational motion
- Tower - support rotor and nacelle
- Lattice - welded small structure support
- Tubular - singular tube or conic shape support
- Turns Ratio - ratio between number of turns in primary and secondary windings
U
- Universal Motor - Type of motor that can work with both DC and single phase AC
- Upwind Turbine - Wind turbine where blades are in front of tower and wind reaches blades before tower
V
- Variable Slip Mode - Way of operation where wound rotor induction generator used with some power extracted
- Variable Speed Mode - Synchronous generator that can operate at different instead of singular speed
- VAWT - Vertical Axis Wind Turbine not sensitive to wind direction changes
- Vector - quantity with both magnitude and direction
- Volt - Electrical potential
- Volt-Ampere - unit of measurement used to express apparent power, when voltage and current out of phase
- VAR - Volt Ampere Reactive - measures reactive power
W
- Watt - 1 Joule per second
- Wind Data - Statistical information gathered about wind in a region
- Wind Farm - region of multiple wind generators also called wind park
- Wind Vane - measures wind direction
- Work - used energy
- Worm gear - high gear ratio used to reduce speed, driven gear cannot force drive gear to rotate
- WRIM - Wound rotor induction machine whose rotor contains winding instead of squirrel cage
- Wye Connection - also called star connection
Y
- Yaw - action of orienting a wind turbine into direction of wind
- Yaw Gear - gear system to rotate turbine for yaw motion
- Yaw System - Entire gears and motors involved in Yaw motion of turbine
