Small Wind Electric Systems: An Arizona Consumer's Guide

Small Wind Electric Systems 21Glossary of TermsAirfoil—The shape of the blade crosssection,which for most modern horizontalaxis wind turbines, is designedto enhance the lift and improve turbineperformance.Ampere-hour—A unit of for the quantityof electricity obtained by integratingcurrent flow in amperes over thetime in hours for its flow; used as ameasure of battery capacity.Anemometer—A device to measurethe wind speed.Average wind speed—The mean windspeed over a specified period of time.Blades—The aerodynamic surfacethat catches the wind.Brake—Various systems used to stopthe rotor from turning.Converter—See Inverter.Cut-in wind speed—The wind speedat which a wind turbine begins togenerate electricity.Cut-out wind speed—The wind speedat which a wind turbine ceases togenerate electricity.Density—Mass per unit of volume.Downwind—On the opposite sidefrom the direction from which thewind is blowing.Furling—A passive protection for theturbine where typically the rotor foldseither up or around the tail vane.Grid—The utility distribution system.The network that connects electricitygenerators to electricity users.HAWT—Horizontal axis wind turbine.Inverter—A device that converts directcurrent (DC) to alternating current(AC).kW—Kilowatt, a measure of powerfor electrical current (1000 watts).kWh—Kilowatt-hour, a measureof energy equal to the use of onekilowatt in one hour.MW—Megawatt, a measure of power(1,000,000 watts).Nacelle—The body of a propeller-typewind turbine, containing the gearbox,generator, blade hub, and other parts.O&M Costs—Operation and maintenancecosts.Power Coefficient—The ratio of thepower extracted by a wind turbineto the power available in the windstream.Power curve—A chart showing awind turbine's power output acrossa range of wind speeds.PUC—Public Utility Commission, astate agency which regulates utilities.In some areas known as Public ServiceCommission (PSC).PURPA—Public Utility RegulatoryPolicies Act (1978), 16 U.S.C. § 2601.18CFR §292 that refers to smallgenerator utility connection rules.Rated output capacity—The outputpower of a wind machine operatingat the rated wind speed.Rated wind speed—The lowest windspeed at which the rated outputpower of a wind turbine is produced.Rotor—The rotating part of a windturbine, including either the bladesand blade assembly or the rotatingportion of a generator.Rotor diameter—The diameter of thecircle swept by the rotor.Rotor speed—The revolutions perminute of the wind turbine rotor.Start-up wind speed—The wind speedat which a wind turbine rotor willbegin to spin. See also cut-in windspeed.