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Otherpower - Wind Power Terms Category: Sciences > Wind power terms Date & country: 28/01/2011, USA Words: 173

AC
See Alternating Current

Airfoil
The cross section profile of the leeward side of a wind generator blade. Designed to give low drag and good lift. Also found on an airplane wing.

Air Gap
In a permanent magnet alternator, the distance between the magnets and the laminates.

Alternating Current
Electricity that changes direction periodically. The period is measured in Cycles per Second (Hertz, Hz).

Alternator
A device that produces Alternating Current from the rotation of a shaft.

Amperage
A unit of electrical current, equal to Coulombs per second. This is the flow rate of electrons moving through a circuit, very roughly analogous to gallons per minute flowing from a faucet.

Ampere-Hour
A measure of energy quantity, equal to amperes times hours. Also used to measure battery capacity.

Anemometer
A device that measures wind speed.

Angle of Attack
The angle of relative air flow to the blade chord.

Annealing
A heat treatment process that makes Cold-rolled steel more suitable for forming and bending.

Area of a Circle
Pi multiplied by the Radius squared.

Armature
The moving part of an alternator, generator or motor. In many PM alternator designs, it carries the magnets and is attached to the blades and hub. Also called a Rotor.

Axial Alternator
An alternator design where a flat disc carrying magnets on the face (the Armature) rotates near a flat disc carrying coils (the Stator).

Axis
The centerline of a rotating object's movement.

Balancing
With wind turbine blades, adjusting their weight and weight distribution through 2 axes so that all blades are the same. Unbalanced blades create damaging vibration.

Battery
An electrochemical device for storing energy.

Battery Bank
An array of Batteries connected in series, parallel, or both.

Bearing
A device that transfers a force to structural supports. In a wind generator, bearings allow the Shaft to rotate freely, and allow the machine to Yaw into and out of the wind.

Belt
A device for transferring power from a rotating shaft to a generator. Allows the use of Pulleys to change the ratio of shaft speed to and from the generator.

Betz Coefficient
59.3 percent. This is the theoretical maximum efficiency at which a wind generator can operate, by slowing the wind down. If the wind generator slows the wind down too much, air piles up in front of the blades and is not used for extracting energy.

Blade
The part of a wind generator rotor that catches the wind.

Brakedrum Windmill
A home-built wind generator design by Hugh Piggott of Scotland.

Braking System
A device to slow a wind turbine's shaft speed down to safe levels electrically or mechanically.

Bridge Rectifier
An array of diodes used to convert Alternating Current to Direct Current. Single-phase bridge rectifiers use 4 diodes, 3-phase bridge rectifiers use 6 diodes.

Brushes
Devices for transferring power to or from a rotating object. Usually made of carbon-graphite.

Ceramic Magnets
See Ferrite Magnets.

Chord
The width of a wind turbine blade at a given location along the length.

Coercivity
The amount of power needed to magnetize or demagnetize a permanent magnet. Measured in MegaGauss Oersted (mGO)

Cogging
The cyclic physical resistance felt in some alternator designs from magnets passing the coils and gaps in the laminates. Detrimental to Start-up.

Coil
A length of wire wound around a form in multiple turns.

Cold-Rolled Steel
Steel processed by working at room temperatures. More expensive than hot-rolled steel.

Commutator
The rotating part of a DC generator.

Concave
A surface curved like the interior of a circle or sphere.

Convex
A surface curved like the exterior of a circle or sphere.

Cowling
See Nacelle.

Current
See Amperage.

Cut-In
The rotational speed at which an alternator or generator starts pushing electricity hard enough (has a high enough voltage) to make electricity flow in a circuit.

Cyanoacrylate
A fast-setting, hard and brittle adhesive. See Superglue®.

Cycles per Second
Measured in Hertz. In electricity, it is the number of times an AC circuit reaches both minimum and maximum values in one second.

Darrieus
A Vertical Axis Wind Turbine design from the 1920s and 1930s by F.M. Darrieus, a French wind turbine designer.

DC
See Direct Current

Delta
A 3-phase alternator wiring configuration in which all phases are connected in Series.

Diameter
A straight line passing through the center of a circle, and ending on both edges. Equal to 2 times the Radius.

Diode
A solid-state device that allows electricity to flow in only one direction.

Downwind
Refers to a Horizontal Axis Wind Turbine in which the hub and blades point away from the wind direction, the opposite of an Upwind turbine.

Drag
In a wind generator, the force exerted on an object by moving air. Also refers to a type of wind generator or anemometer design that uses cups instead of a blades with airfoils.

Dump Load
A device to which wind generator power flows when the system batteries are too full to accept more power, usually an electric heating element. This diversion is performed by a Shunt Regulator, and allows a Load to be kept on the Alternator or Generator.

Duty Cycle
In a circuit, the ratio of off time to on time.

Dynamo
A device that produces Direct Current from a rotating shaft. See Generator.

Eddy Currents
Currents that flow in a substance from variations in magnetic induction. See also Lenz Effect. Laminates are used to prevent eddy currents, which cause physical and electrical resistance in an alternator or transformer, therefore wasting power.

Efficiency
The ratio of energy output to energy input in a device.

Electromagnet
A device made of wire coils that produces a magnetic field when electricity flows through the coils.

Epoxy
A 2-part adhesive system consisting of resin and hardener. It does not start to harden until the elements are mixed together. NOT compatible with Fiberglas® Resin.

Excitation
Using an electric current to create a magnetic field. See Electromagnet.

Fatigue
Stress that causes material failure from repeated, cyclic vibration or stress.

Ferrite Magnets
Also called Ceramic Magnets. Made of Strontium Ferrite. High Coercivity and Curie Temperature, low cost, but brittle and 4-5 times weaker than NdFeB magnets.

Fiberglas® Resin
Another 2-part adhesive system, NOT compatible with Epoxy. Often used for making castings, since it is much cheaper than Epoxy.

Field
See Magnetic Field

Flux
See Magnetic Field

Freewheeling
a wind generator that is NOT connected to a Load is freewheeling, and in danger of self-destruction from overspeeding.

Frequency
See Cycles per Second.

Furling
The act of a wind generator Yawing out of the wind either horizontally or vertically to protect itself from high wind speeds.

Furling Tail
A wind generator protection mechanism where the rotor shaft axis is offset horizontally from the yaw axis, and the tail boom is both offset horizontally and hinged diagonally, thus allowing the tail to fold up and in during high winds. This causes the blades to turn out of the wind, protecting the machine.

Gauss
A unit of magnetic induction, equal to 1 Maxwell per square centimeter. Higher Gauss measurements mean more power can be induced to flow in an alternator. Gauss readings can be increased by putting steel behind magnets, stacking magnets, or using larger or higher-grade magnets.

Gearing
Using a mechanical system of gears or belts and pulleys to increase or decrease shaft speed. Power losses from friction are inherent in any gearing system.

Generator
A device that produces Direct Current from a rotating shaft.

Governor
A device that regulates the speed of a rotating shaft, either electrically or mechanically.

Guy Anchor
Attaches tower guy wires securely to the earth.

Guy Radius
The distance between a wind turbine tower and the guy anchors.

Guy Wire
Attaches a tower to a Guy Anchor and the ground.

HAWT
See Horizontal Axis Wind Turbine.

Hertz
Frequency measurement. See Cycles per Second

Horizontal Axis Wind Turbine
A "normal" wind turbine design, in which the shaft is parallel to the ground, and the blades are perpendicular to the ground.

Hub
The center of a wind generator rotor, which holds the blades in place and attaches to the shaft.

Impedance
See Resistance.

Induction
The production of a magnetic field by the proximity of a electric charge or the production of a magnetic field by proximity of an electric charge.

Induction Motor
An AC motor in which the rotating armature has no electrical connections to it (ie no slip rings), and consists of alternating plates of aluminum and steel.

Kerf
The width of a cut made by a saw.

Kilowatt
1000 Watts (see Watt)

kW
See Kilowatt.

Laminations
Electrical circuit core parts, found in motors, generators, alternators and transformers. When core parts are subjected to alternating electrical or magnetic fields, the buildup of Eddy Currents causes physical and electrical power loss. Laminations are made of thin strips of materials that make good temporary magnets and poor permanent magnets, and each strip is insulated electrically from the ne...

Leading Edge
The edge of a blade that faces toward the direction of rotation.

Leeward
Away from the direction from which the wind blows.

Lenz Effect
See also Eddy Currents. From H.F.E Lenz in 1833. Electromotive force is induced with variations in magnetic flux. It can be demonstrated physically in many different ways

Lift
The force exerted by moving air on asymmetrically-shaped wind generator blades at right angles to the direction of relative movement. Ideally, wind generator blades should produce high Lift and low Drag.

Live
A circuit that is carrying electricity. When live, it can shock you.

Load
Something physical or electrical that absorbs energy. A wind generator that is connected to a battery bank is loaded. A disconnected wind generator is NOT loaded, so the blades are free to spin at very high speed without absorbing any energy from the wind, and it is in danger of destruction from overspeeding.

Losses
Power that is harvested by a wind generator but is not transferred to a usable form. Losses can be from friction, electrical resistance, or other causes.

Magnet
A body that attracts ferromagnetic materials. Can be a Permanent magnet, Temporary Magnet, or Electromagnet.

Magnetite
A common Iron-containing mineral with ferromagnetic properties.

Magnet Wire
The kind of wire always used in making electromagnets, alternators, generators and motors. Uses very thin enamel insulation to minimize thickness and maximize resistance to heat.

Magnetic Circuit
The path in which magnetic flux flows from one magnet pole to the other.

Magnetic Field
Magnetic fields are historically described in terms of their effect on electric charges. A moving electric charge, such as an electron, will accelerate in the presence of a magnetic field, causing it to change velocity and its direction of travel. An electrically charged particle moving in a magnetic field will experience a force (known as the Lorentz force) pushing it in a direction perpendicular...

Maximum Energy Product
Determines how good a magnet that different materials can make. Technically, the amount of energy that a material can supply to an external magnetic circuit when operating within its demagnetization curve.

MegaGauss Oersted
Magnetic force measurement, see Maximum Energy Product.

MGOe
See MegaGauss Oersted.

Moment
A force attempting to produce motion around an axis.

Nacelle
The protective covering over a generator or motor.

NdFeB
See Neodymium-Iron-Boron Magnet.

Neodymium-Iron-Boron Magnet
The composition of the most powerful Permanent Magnets known to man. The materials are mined, processed, and sintered into shape. Then, they are subjected to an extremely strong magnetic field and become Permanent Magnets.