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Wind Power Terms Defined

Hurricane Wind Power Terms

Starting out trying to read and understand and wind power related can be confusing and frustrating. Her is our dictionary of terms to start with and if you see one you would like added or if we are missing something feel free to contact us so we can make an update.


Glossary of WIND POWER Terms

Airfoil—The shape of the blade cross-section, which for most modern horizontal axis wind turbines, is designed to enhance the lift and improve turbine performance.

Amperage,Amps-This is a name sometimes used in place of current. It is used because the electrical current is measured in Amperes (Amps). By definition, 1 Ampere = the current that will cause silver to be deposited at a rate of 0.001118 grams per second when passed through a solution of silver nitrate. A measurement of the amount of electric current

Ampere-hour—A unit for the quantity of electricity obtained by integrating current flow in amperes over the time in hours for its flow; used as a measure of battery capacity.

Anemometer—A device to measure the wind speed.

Atom-The smallest unit of matter. Scientists so far have found 112 different kinds of atoms. Everything in the world is made of different combinations of these atoms.

Average wind speed—The mean wind speed over a specified period of time.

Biomass-Organic materials, such as wood by-products and agricultural wastes, that can be burned to produce energy or converted into a gas and used for fuel.

Blades—The aerodynamic surface that catches the wind.

Brake—Various systems used to stop the rotor from turning.

Charge-The electric charge of an object is a measure of how much electricity is there. It is similar to the mass of an object when you are dealing with gravity, but unlike mass charge can be either positive (+) or negative (-). At the atomic level charge is measured in multiples of the charge on an electron (-1), in larger cases the usual measurement is the Coulomb.

Conductor-A conductor is a material that allows electricity to move through it easily. That is, it is a material with low electrical resistance, one in which a fairly small voltage will produce a fairly large current. The opposite of an insulator. Something that allows electricity to flow through it easily. Water and most metals are good conductors. Conductors can allow electricity to flow through them because the electrons in their atoms move between atoms very easily.

Converter—See Inverter.

Coulomb-The Coulomb is the unit normally used to measure large charges. 1 Coulomb = the amount of electricity passing a given point in 1 second at a current of 1 Ampere.

Current-The electrical current is simply a measure of how much electricity passes a given point in a fixed amount of time. It is similar to the current of a stream or river, which measures how much water passes a given point in a fixed amount of time. Electrical current is measured in Amperes (Amps). The movement or flow of electricity.

Cut-in wind speed—The wind speed at which a wind turbine begins to generate electricity.

Cut-out wind speed—The wind speed at which a wind turbine ceases to generate electricity.

Density—Mass per unit of volume.

Distribution Lines-Power lines that carry electricity through towns and neighborhoods to homes and businesses. Distribution lines can run overhead or underground.

Downwind—On the opposite side from the direction from which the wind is blowing.

Electric Field -The space near a charged BODY where other charges are affected. Similar to the gravitational field near a planet, except that it can also repel. The term is also used to describe how the field will affect other charges (which way and how much it will accelerate them).

Electricity-The flow of electrons.

Electron-The basic particle that orbits the nucleus of an atom. The flow of electrons produces electricity.

Energy-The ability to do work. People get energy from food. Your toaster and your washing machine get their energy from electricity.

Faraday Cage -The name given to a device that shields its inside from electric fields generated by static electricity. Usually a complete conductive shell, it collects stray charges and, because like charges repel, stores them on the outside surface (where they can be further apart than on the inside). The electric fields generated by these charges then cancel each other out on the inside of the cage. Often used to protect sensitive radio equipment.

Fission-The splitting apart of an atom's nucleus, releasing a large amount of heat energy.

Fluorescent bulb-A light bulb that emits light because the gas inside it glows when it is charged by electricity.

Frequency -For an alternating current, the frequency is the number of times that the current goes through a complete cycle per second. It is measured in Hertz (cycles per second).

Fuel cell-A technology that produces electricity through a chemical reaction similar to that found in a battery.

Furling—A passive protection for the turbine where typically the rotor folds either up or around the tail vane.

Generator-A machine that converts mechanical energy into electrical energy.

Geothermal energy-Energy that is generated by converting hot water or steam from deep beneath the Earth's surface into electricity.

Grid—The utility distribution system. The network that connects electricity generators to electricity users.

Ground-The ground is an arbitrarily decided point whose voltage is taken as zero. In many situations, equipment is connected physically to the actual, dirt ground, so that voltage is taken as zero--hence the name. In England the term "earth" is used, for the same reason. To be "grounded" means to be connected to a place that is maintained at the ground voltage.

Hydroelectricity-Electricity that is generated when falling water makes a turbine spin.

HAWT—Horizontal axis wind turbine.

Incandescent bulb-A light bulb that emits light due to the glowing of a heated filament inside it.

Insulator-An insulator is a material that electricity has a hard time moving through, if it can at all. For a true insulator it takes a very high voltage to produce any current at all, and that often results in damage to the insulator. The opposite of a conductor. Something that does not allow electricity to flow through it easily. Glass and special rubber are good insulators. Insulators do not allow electricity to flow through them easily because the electrons in their atoms do not move easily from atom to atom.

Induction-Induction is the process by which charge is moved in a conductor by the presence of an electric field. In wires this will lead to a current, in discrete conducting objects it will lead to local charging--ie. the side near the inducing charge will become the opposite charge and the far side will acquire a similar charge leaving the overall charge of the object unchanged.

Inverter—A device that converts direct current (DC) to alternating current (AC).

Kilowatt hour-One kilowatt of electricity produced or used in one hour.

Kilowatt-1,000 watts of electricity.

kWh—Kilowatt-hour, a measure of energy equal to the use of one kilowatt in one hour.

kW—Kilowatt, a measure of power for electrical current (1000 watts).

Megawatt-One million watts. 1,000,000 watts of power or 1,000 kilowatts.

MW—Megawatt, a measure of power (1,000,000 watts).

Nacelle—The body of a propeller-type wind turbine, containing the gearbox, generator, blade hub, and other parts.

Natural gas-A gas used as a fuel, which is formed naturally in the earth when organic material decomposes under pressure.

Neutron-A basic particle in an atom's nucleus that has a neutral electrical charge.

Nucleus-The center of an atom. The nucleus contains tiny particles called protons and neutrons. Orbiting around the nucleus are electrons.

O&M Costs—Operation and maintenance costs.

Ohm-The Ohm is the unit of electrical resistance.

Photovoltaic cell-A device that changes sunlight directly into electricity.

Power Coefficient—The ratio of the power extracted by a wind turbine to the power available in the wind stream.

Power curve—A chart showing a wind turbine's power output across a range of wind speeds.

Power line-A wire used to carry electricity. Power lines are located high overhead or buried underground.

Power plant-A place where electricity is generated.

Proton-A basic particle in an atom's nucleus that has a positive electrical charge.

PUC—Public Utility Commission, a state agency which regulates utilities. In some areas known as Public Service Commission (PSC).

PURPA—Public Utility Regulatory Policies Act (1978), 16 U.S.C. § 2601.18 CFR §292 that refers to small generator utility connection rules.

Rated output capacity—The output power of a wind machine operating at the rated wind speed.

Rated wind speed—The lowest wind speed at which the rated output power of a wind turbine is produced.

Resistance-Electrical resistance is a measure of how hard it is for a current to pass through a given material. It is similar to the way that it is harder for you to walk through water than air. It is usually measured in Ohms.

Rotor diameter—The diameter of the circle swept by the rotor.

Rotor speed—The revolutions per minute of the wind turbine rotor.

Rotor—The rotating part of a wind turbine, including either the blades and blade assembly or the rotating portion of a generator.

Solar energy-Electricity produced from the sun's radiation.

Substation-A facility where transformers lower or increase electricity's voltage.

Start-up wind speed—The wind speed at which a wind turbine rotor will begin to spin. See also cut-in wind speed.

Static Electricity -Static electricity (or just "static") is the name used to cover those phenomena that involve charges that are not moving (much)-ie. they are static. The other form of electrical phenomena is current electricity, where the charges are moving in a large-scale, organized way.

Swept area—The area swept by the turbine rotor, A = pi R 2 , where R is the radius of the rotor.

Tip speed ratio—The speed at the tip of the rotor blade as it moves through the air divided by the wind velocity. This is typically a design requirement for the turbine.

Transformer -A transformer is simple a device that transforms electricity form one voltage to another. The power coming out of the transformer cannot exceed that going in, so the output current is reduced in direct proportion to the gain in voltage. A device used to increase or decrease electricity's voltage and current.

Transmission lines -Power lines that carry high-voltage electricity long distances.

Turbine-A device used in the generation of electricity. It has a shaft with blades at one end and electromagnets at the other. Water or steam or some other energy source pushes the blades, which make the shaft and the magnets spin very fast. The magnet end is surrounded by heavy coils of copper wire, and the spinning magnets cause electrons in the wire to begin to move, creating electricity.

Turbulence—The changes in wind speed and direction, frequently caused by obstacles.

Upwind—On the same side as the direction from which the wind is blowing—windward.

Utility-A company or other organization that provides a public service, such as supplying electricity, natural gas, or water.

VAWT—Vertical axis wind turbine.

Voltage, Volts -Voltage is a measure of the force on a unit charge at a given point in space due to all the other "local" charges. It is similar to the gravitational pull on a unit mass in space, except that, since charges can be + and -, the force can be attractive or repulsive. 1 Volt = force required to produce a current of 1 Ampere in a wire of 1 Ohm resistance. A measure of the pressure under which electricity flows.

Wattage, Watts -A measure of the amount of work done by a certain amount or amperage of electric current at a certain pressure or voltage.

Wind farm—A group of wind turbines, often owned and maintained by one company. Also known as a wind power plant.

Yaw—The movement of the tower top turbine that allows the turbine to stay into the wind.