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

Ohm's Law
The basic math needed for nearly all electrical calculations. Please see a dictionary or Pocket Ref for all of the variations on Ohm's Law! E=I*R (voltage(E)=amperage(I)*resistance(R)), and all of the algebraic variations of this (I=E/R, R=E/I). Also, for DC circuits, Watts=Volts*Amps. For AC circuits, Watts=Amps * Volts * Cosine of phase angle theta.

Open-Circuit Voltage
The voltage that a alternator or generator produces when it is NOT connected to a Load.

Parallel
In DC electrical circuits such as a battery bank or solar panel array, this is a connection where all negative terminals are connected to each other, and all positive terminals are connected to each other. Voltage stays the same, but amperage is increased. In AC circuits such as a wind generator alternator, each parallel coil is connected to common supply wires, again increasing amperage but leavi...

Permanent Magnet
A material that retains its magnetic properties after an external magnetic field is removed.

Permanent Magnet Alternator
An Alternator that uses moving permanent magnets instead of Electromagnets to induce current in coils of wire.

Phase
The timing of AC current cycles in different wires. 3-phase alternators produce current that is cyclically timed between 3 different wires and a common wire, while single phase produces it in only 1 wire and a common. In a 3-phase alternator, wire #1 receives a voltage peak, then wire #2 receives a peak, then wire #3, and so on. A diagram is an easier way to explain phase, check out Windstuffnow.c...

Pillow Blocks
Bearings that support a horizontal shaft.

Pitch
See Setting Angle.

PM
See Permanent Magnet.

PMA
See Permanent Magnet Alternator.

Poles
A way of picturing magnetic phenomena. All magnets are considered to be "dipoles", having both a North pole (which would point North if used in a compass) and a South pole (which would point South if used in a compass. In an alternator, generator, or motor the number of Poles is a measure of how many coils, permanent magnets or electromagnets are in the armature or stator.

Prop
Slang term for Propeller.

Propeller
The spinning thing that makes an airplane move forward. Often incorrectly used (by Otherpower.com also!) to describe a wind turbine Rotor.

Pulley
A device for transferring power when using Belts as Gearing. Changing to smaller or larger Pulleys changes the gear ratio, and can be used to make a shaft turn faster or slower than the shaft that is providing its power.

Pulse Width Modulation
(abbrev. PWM) A regulation method based on Duty Cycle. At full power, a pulse-width-modulated circuit provides electricity 100 percent of the time. At half power, the PWM is on half the time and off half the time. The speed of this alternation is generally very fast. Used in both solar wind regulators to efficiently provide regulation.

PWM
See Pulse Width Modulation.

Radius
The distance between the center of a circle and the outside.

Rare-Earth Magnets
See Neodymium-Iron-Boron magnets.

Rated Power Output
Used by wind generator manufacturers to provide a baseline for measuring performance. Rated output may vary by manufacturer. For example, one manufacturer's 1500 watt turbine may produce that amount of power at a 30 mph windspeed, while another brand of 1500 watt turbine may not make 1500 Watts until it gets a 40 mph windspeed! So read manufacturer's ratings statements very carefully.

Radial
An alternator design in which the armature magnets are attached to the outside circumference of a disc, with the stator coils mounted around the outside.

Rectifier
See Diode.

Regulator
A device to adjust incoming power so as to avoid overcharging a battery bank. In solar power, the regulator generally just turns the solar array off when the batteries are full. With a wind generator, the regulator generally diverts all or part of the incoming power to a Dump Load when the batteries fill, thus keeping a Load on the wind generator so it will not Freewheel.

Relay
An electromechanical switch that uses a small amount of incoming electricity to charge an electromagnet, which physically pulls down a connecting switch to complete a circuit. This allows a low-power circuit to divert the electricity in a high-power circuit.

Resistance
The voltage per amp needed to make electricity flow through a wire. See Ohm's Law.

Root
The area of a blade nearest to the hub. Generally the thickest and widest part of the blade.

Rotor
1) The blade and hub assembly of a wind generator. 2) The disc part of a vehicle disc brake. 3) The armature of a permanent magnet alternator, which spins and contains permanent magnets.

RPM
Revolutions Per Minute. The number of times a shaft completes a full revolution in one minute.

Savonius
A vertical-axis wind turbine design by S.J. Savonius of Finland from the 1920s and 30s. Shaped like a barrel split from end to end and offset along the cut. They are drag machines, and thus give very low rpm but lots of torque.

Series
In DC electrical circuits such as a battery bank or solar panel array, this is a connection where all the negative terminals are connected to the neighboring positive terminals. Voltage increases, but amperage stays the same. In AC circuits such as a wind generator alternator, each coil is connected to the one next to it, and so on, again increasing voltage but leaving amperage the same. Opposite ...

Servo Motor
A motor used for motion control in robots, hard disc drives, etc. Generally designed more like an alternator than a standard motor, most Servos need special control circuitry to make them rotate electrically. Some can be used in reverse to generate alternating current.

Setting Angle
The angle between the blade Chord and the plane of the blade's rotation. Also called Pitch or blade angle. A blade carved with a Twist has a different setting angle at the Tip than at the Root.

Shaft
The rotating part in the center of a wind generator or motor that transfers power.

Short Circuit
1) Parts of a circuit connected together with only the impedance of the leads between them. 2) In wind generators, connecting the output leads directly together so as to heavily load a generator in high winds. This creates a "short" circuit path back to the generator, bypassing all other loads.

Shunt
An electrical bypass circuit that proportionally divides current flow between the shunt and the shunted equipment. It also allows high current measurements with low-current equipment.

Shunt Regulator
A bypass device for power not needed for charging batteries. When batteries are full, the regulator shunts all or part of the excess power to a Dump Load to protect the batteries from overcharging damage.

Slip Ring
Devices used to transfer electricity to or from rotating parts. Used in wound-field alternators, motors, and in some wind generator yaw assemblies.

Star
A coil connection scheme for 3 phase alternators and generators in which all 3 coil phases are connected in parallel

Start-Up
The windspeed at which a wind turbine rotor starts to rotate. It does not necessarily produce any power until it reaches cut-in speed.

Stationary
With wind generator towers, a tower that does not tilt up and down. The tower must be climbed or accessed with a crane to install or service equipment at the top.

Stator
The part of a motor, generator or alternator that does not rotate. In permanent magnet alternators it holds the coils and laminates.

SuperGlue®
Cyanoacrylate adhesive. Fast bonding glue, easy to find in different viscosities. Sets on its own, and sets instantly when sprayed with an accelerator chemical. Hard, but somewhat brittle. Does not react adversely with Fiberglas® resin or epoxy.

Tail
See Vane. The proper term is actually Vane, but Tail is commonly used.

Tail Boom
A strut that holds the tail (Vane) to the wind generator frame.

Tape Drive Motor
A type of permanent magnet DC motor often used as a generator in small wind generator systems.

Taper
The change in wind turbine blade width (chord) along the length.

Temporary Magnet
A material that shows magnetic properties only while exposed to an external magnetic field.

Thrust
In a wind generator, wind forces pushing back against the rotor. Wind generator bearings must be designed to handle thrust or else they will fail.

Thrust Bearing
A bearing that is designed to handle axial forces along the centerline of the shaft

Tilt-Up
A tower that is hinged at the base and tilted up into position using a gin pole and winch or vehicle. Wind turbines on tilt-up towers can be serviced on the ground, with no climbing required.

Tip
The end of a wind generator blade farthest from the hub.

Tip Speed Ratio
The ratio of how much faster than the windspeed that the blade tips are moving. Abbreviation TSR.

Torque
Turning force, equal to force times radius. See also Moment.

Tower
A structure that supports a wind generator, usually high in the air.

Trailing Edge
The edge of a blade that faces away from the direction of rotation.

Transformer
Multiple individual coils of wire wound on a laminate core. Transfers power from one circuit to another using magnetic induction. Usually used to step voltage up or down. Works only with AC current.

TSR
See Tip Speed Ratio.

Turn
In winding stator coils, this is one loop of wire around a form. A coil will often be referred to by how many turns of a certain gauge wire are in each coil.

Twist
In a wind generator blade, the difference in Pitch between the blade root and the blade tip. Generally, the twist allows more Pitch at the blade root for easier Startup, and less Pitch at the tip for better high-speed performance.

Vane
A large, flat piece of material used to align a wind turbine rotor correctly into the wind. Usually mounted vertically on the tail boom. Sometimes called a Tail.

Variable Pitch
A type of wind turbine rotor where the attack angle of the blades can be adjusted either automatically or manually.

VAWT
See Vertical Axis Wind Turbine.

Vertical Axis Wind Turbine
A wind generator design where the rotating shaft is perpendicular to the ground, and the cups or blades rotate parallel to the ground.

Voltage
A measure of electrical potential difference. One volt is the potential difference needed in a circuit to make one Ampere flow, dissipating one Watt of heat.

Volt-Amp
In an AC circuit, this is Volts * Amps, without factoring in the power factor, derived from the phase angle. See also Watt.

Watt
One Joule of electrical energy per second. In DC circuits, Watts=Volts * Amps. In AC circuits, Watts=Volts * Amps * the cosine of the phase angle. See also Volt-Amp.

Wild AC
Alternating Current that varies in Frequency.

Wind Generator
A device that captures the force of the wind to provide rotational motion to produce power with an alternator or generator.

Windmill
A device that uses wind power to mill grain into flour. But informally used as a synonym for wind generator or wind turbine, and to describe machines that pump water with wind power.

Wind Turbine
A machine that captures the force of the wind. Called a Wind Generator when used to produce electricity. Called a Windmill when used to crush grain or pump water.

Windward
Toward the direction from which the wind blows.

Yaw
Rotation parallel to the ground. A wind generator Yaws to face winds coming from different directions.

Yaw Axis
Vertical axis through the center of gravity.

H-Rotor
A Vertical Axis Wind Turbine design.