Wind Turbines and wind power made easy

Wind turbines, like aircraft propeller blades, turn in the moving air and

  1. Centre for Application of renewable Energy
    Wind turbines, like aircraft propeller blades, turn in the moving air and
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    Wind Turbines and wind power made easy
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    • 1. Vision StatementWe strive to preserve natural resources to the maximum extentp act cab epracticable by developing, sourcing and commission of the latest de e op g, sou c g a d co ss o o t e atesttechnology and solutions for efficient use of such resources. In expressingthis concern as part of our daily activity and in acting upon this premise,we Endeavour to be recognised as exemplary in this field field   We strive to educate and impart a partnership to save the environmentto live a world better than what we found for our children.• "Something from Nothing",• "Treasure from Trash" and• "Gold from Garbage
    • 3. BEFORE You Erect a TurbineAnemometers : It i essential tA t is ti l to Build your own anemometer: We builtknow the real wind speed in any wind an accurate anemometer for under Rsgenerator installation, commercial or 500 using plastic Easter eggs. See ithomemade.homemade This allows you to see if here! It counts frequency with a simplethe machine is performing correctly,and extremely high wind speeds might circuit, and can be adapted to use withbe a clue that you should shut the mill y computer data acquisition equipment.down for the duration of the storm. Ifyou plan on investing significant Logging anemometer kit: This ingeniousmoney in wind power, a logging kit is from Australia and costs less thananemometer might help you decide if f Rs5000 R 5000 It t k wind speed and tracks i d d dyour local wind resource is worth the direction, and logs data to its owninvestment. Commercial anemometers memory, including average and peakand weather stations are very readings. And, readings And it interfaces directly to aexpensive, but can be found with a PC...your wind data can import livequick Google can also try right into a spreadsheet!one of the homebrew options below.
    • 4. Location First, figure out the direction from which the prevailing winds in your area usually come. come You can determine this by observation during wind storms, and by looking at the trees near your site. Trees that are all leaning the same direction and that have branches mostly on one side of the trunk are a good indication of p prevailing wind speed and direction. g p Local airports and weather stations can sometimes provide you with this information. *** A Logging anemometer that also records wind direction can be useful here too, though expensive.
    • 5. HeightFlying a wind generator close tothe ground is like mounting solarpanels in the shade! Your windgenerator should b l h ld be located atdleast 30 feet above anyobstruction within 300 feet in anydirection—many sourcesrecommend even more. Shorttowers in turbulent locationscause drastically reduced poweroutput, and extreme physicalstresses on the turbine andtower.
    • 6. Distance: The distance between your windgenerator and your batteries canalso be a problem—the closer thebetter,better to avoid losses in longwires and to keep the wire sizerequired down to a reasonablethickness and cost. 12 voltthi k d t ltsystems are the worst for powertransmission losses‐‐you end upneeding very thick wire. A 24v or48v battery bank can save you bigmoney on wire!
    • 7. TowerCheck out our TOWERS page for somehome‐brewed solutions that are cheapand easy to fabricate, plus lots of detailsand pictures. Theres also lots of towerinformation, discussion and picturesavailable by Searching the Other powerdiscussion board for towers.Your tower must be extremely sturdy,well‐anchored, and tall enough to getabove obstructions. Weve seen 1.5 inchsteel pipe bend like a pipe cleaner in 50mph winds, underneath a wind machinewith only an 8‐foot rotor. Some windenergy guidelines tell you to plan onspending at LEAST as much on your di t htower and power wiring as on the windgenerator itself!
    • 8. TowerDo you like to climb? The two basic kinds oftower are the Tilt‐Up and Stationary. Astationary tower is the most sturdy andtrouble‐free,trouble free but you have to climb it toinstall, maintain or remove the windmachine.A crane is often used for installation, anexpensive proposition‐‐though you can do ityourself by climbing the tower and movinga gin pole up it as you add each newsection. If climbing towers disagrees withyou, go for a tilt‐up. Then all maintenance tilt up.can be performed while standing safely onsolid ground.
    • 9. Tower : Roof mount? Roof mount? We strongly recommend against mounting a wind generator on your roof. The winds near rooftop level are very slow and turbulent, and power output will be drastically reduced This goes for ALL reduced. types of wind turbine, not just ours. Again, your turbine needs to be mounted at least 30 feet above anything within 300 feet in any direction Vibration is also an issue direction. issue. Though the manufacturer says it works, we have observed first‐hand the vibration and noise d i a windstorm i t i during i dt in two diff different t roof is VERY noticeable and irritating. And keep in mind that the very small unit (only a 1.3 meter prop) that makes very little power a larger mill would power...a be unbearable, and possibly dangerous to your house itself.
    • 10. Tower : **Roof mount? Roof Though th manufacturer says it works, we Th h the f t k have observed first‐hand the vibration and noise during a windstorm in two different roof is VERY noticeable and irritating. And keep in mind that the very small unit (only a 1.3 meter prop) that makes very little power...a larger mill would be unbearable and possibly unbearable, dangerous to your house itself. Most commercial and homemade wind generators dont make much physical noise, but some vibration is unavoidable due to the nature of permanent magnet alternators. Listen to the vibration of Wards 7 foot diameter windmill ** (12 second .WAV file, 140K) and hear why we dont recommend roof mounts!
    • 11. ROTOR
    • 12. Speed The h ft Th shaft speed i a very crucial f t i all d is i l factor in ll types of alternator and generator. The unit needs to make higher voltages at lower RPM’s, otherwise it is not suited for wind power use. This goes for all power units...even motors used as generators and alternators should b d d l h ld be rated for low RPM’s. This is also why vehicle alternators are not suited for wind power use. Most commercial wind generators cut in at 8‐12 mph. The generators low‐speed voltage performance, the design of the rotor (the blades and hub), and the wind behavior all factor into where cut‐in will occur.
    • 13. RotorA wind generator gets its power f d from slowing d l down the wind. The bl d h d h bladesslow it down, and the alternator collects the power. BOTH must be correctlydesigned to work together and do this efficiently.We are not experts at blade design...we sort of started in the middle with afunctioning design, and made changes from there. Really, you could make asimple set of blades with a straight 5 degree pitch down the entire length andthey would work JUST FINE! But to really tune in the performance of yourwind generator, its important to payattention to a f f i few factors. ALSO l ALSO‐‐please f i us when we slip up and refer forgive h li d fto the rotor as a "prop" or"propellor"‐ p p‐it doesnt propel anything! Rotor is the proper term, not to be confused withthe rotor of an armature. But we slip up sometimes...
    • 14. Speed Start‐Up Speed‐‐This i th windspeed at St t U S d Thi is the i d d t which the rotor starts turning. It should spin smoothly and easily when you turn it by hand, and keep spinning for a few seconds. Designs that cog from magnetic force or that use gears or pulleys to increase shaft speed will be poor at start up. A good design can start spinning in 5 mph winds and cut in at 7 mph. Cut‐In Speed‐‐A wind generator does not start pushing power into the battery bank until the generator or alternator voltage gets higher than the battery bank voltage. Higher shaft speed means higher voltage in all g generators and alternators, and you want to , y try and get the highest shaft speed possible in low winds‐‐ without sacrificing high‐wind performance.
    • 15. TermsWe try to use the term Generator to describe a machine that produces DirectCurrent (DC), and use the term Alternator to describe a machine that producesAlternating Current (AC). However, the term Generator is also used generically todescribe any machine that produces electricity when the shaft is spun.Options‐‐The alternator or generator is the heart of your wind machine, and itmust be both properly sized to match your swept area, and produce the right typeand voltage of power to match your application Unfortunately there are no application. Unfortunately,commercial or surplus products than can be easily matched to a set of blades forbuilding a wind turbine. Its MUCH more practical to build your own alternator thanto try and adapt a commercial unit that was designed for a completely differentpurpose. If you try that anyway, PM converted i d i motors, DC generators, DC h d inductionbrushless PM motors, vehicle alternators, and induction motors are options...butare marginal performers at best.Application‐‐Wind‐generated electricity can be used for battery charging and forconnection with the power grid. All of our designs and information are aboutbattery charging at this time, since we all live 12 miles from the nearest power line.
    • 16. Single Phase vs. Three Phase--3 vsSingle Phase vs. Three Phase‐‐3 phaseoffers some advantages over single phasein most alternators. Most smallcommercial wind turbines use 3 phasealternators, and then rectify the outputto DC (direct current) for chargingbatteries. When building an alternatorfrom scratch, single phase seemsattractive because it is simple and easy tounderstand. 3 phase is not really anymore difficult.Going 3 phase allows for squeezing more g p q gpower from a smaller alternator. Itsignificantly reduces line loss, and it runswith less vibration. Older single phasealternators we made vibrate much more(and make more noise) than 3 phasemachines.
    • 17. An alternatorAn alternator that uses many windings of thin wire y gwill have better low‐speed performance than one thatuses fewer windings of thicker wire, but higherinternal resistance. This means it will becomeinefficient more quickly when producing higheramperage as wind speeds and power output rise. p g p p pThe formula used to calculate power wasted frominefficiency is AMPS^2 * RESISTANCE = Power wastedas heat in the alternator windings (in watts).Alternator D iAl Design FFactors‐‐Making PM alternators M ki lfrom scratch is sort of a "black art"‐‐there are manyfactors that enter in to it, we try to discuss some ofthem below. And then, you must add in anotherimportant factor, the design of the blades. We discussthat below l We didnt t t building i d illth t b l also. W did t start b ildi windmills and dalternators by doing a bunch of math...we just jumpedright in, made lots of mistakes, and eventually woundup with a satisfactory design by observingperformance and changing one variable at a time. Thedifficultdiffi lt part i getting th b t match b t t is tti the best t h between th theblades and the alternator.
    • 18. MagnetsThe stronger the better The larger stronger, better.and stronger your magnets are, themore power you can produce in asmaller alternator. Neodymium‐Iron‐Boron ("rare earth", NdFeB) are by farthe strongest permanent magnetsknown to man, and are ideal forbuilding permanent magnetalternators. Many older designs callfor strong ceramic magnets, this wasmainly because of price. We do selllarge, high‐gradelarge high grade ceramic magnetsthat are suitable for alternator use,but in practice NdFeB magnets willgive over 4 times as much power inthe same space than ceramics. Plus, h h i lprices on large NdFeB magnets havedropped dramatically since they werefirst invented in the 1980s.
    • 19. Number of PolesA pole is either the North or South pole of a magnet pole magnet.Generally when building an alternator we need aseperate magnet for each pole. The faster thatalternating north and south magnets poles pass thecoils,coils the more voltage and current are produced But produced.surface area is important as well. If we have a verynarrow magnet (required for using many poles), thefield strength would be much weaker over a distancethan a wider magnet So like all things with making magnet.wind turbines, there is a compromise to be made.We choose a number of poles that allows forreasonably sized coils and a good strong magnetic fi ld bl i d il d d t ti fieldthrough whatever air‐gap we wind up with. It mustalways be an even number. For a 3 phase machine welike 4 poles for every 3 coils, although there arecertainly other very feasible options In most cases for options. cases,a 3 phase machine wed have somewhere between 8and 16 poles (magnets) unless perhaps the machinewere to be very large.
    • 20. Air GapAir Gap Gap‐‐This is the distance between themagnets and the laminates in a singlemagnet rotor design, or between twomagnets in a dual magnet rotor design.The smaller the distance, the better thealternator performs. This means itsimportant to keep the coils as flat aspossible, and to make the armature fitvery precisely near the stator...if it isnot perfectly square, the air gap will belarger on one side of the alternatorl id f h lthan the other, and performance willbe compromised. Halving the airgapggives 4 times as much magnetic flux. g
    • 21. Bearings--TheTh operative word h ti d here i STRONG is STRONG.Besides having to withstand vibrationand high rotation speed, there is asignificant amount of thrust back on thebearings from the wind, and it increasesgeometrically as the prop size increases.Thats why weve moved to using y gstandard trailer wheel bearings in ourdesigns, they are tapered and designedto take the thrust loads. The frontbearings in our converted AC inductionmotors have so far held up well, butthey are not designed for that kind ofload.load DC tape drive motors areespecially vulnerable‐‐the front bearingwill eventually fail dramatically in highwinds if extra bearings are not added.
    • 22. Series or Parallel? Star or DeltaWhen ilWh coils are connected i series, t d in ithe voltage increases and so doesresistance. When connected inparallel,parallel voltage stays the same butamperage increases and resistancedecreases. Also, parallel connectionsin an alternator can cause current toflow where you dont want it to,called parasitic losses. The correctconfiguration for your projectdepends on many factors.Windstuff nows 3‐Phase Basics Pagehas some great diagrams that explain3‐phase, star and delta. We wire allof our alternators in Star.
    • 23. WireEnameled magnet wire is always used for winding the stator, because the insulation is very thinand heat‐resistant. This allows for more turns of wire per coil. It is very difficult to strip, use arazor knife or sandpaper, and be sure to strip each lead thoroughly! Choosing the gauge of wire isyet another trade off‐‐thinner gauge wire allows for more turns per coil and thus better voltagefor low‐speed cut‐in, but using longer, thinner wire gives higher resistance and therefore the unitbecomes inefficient faster at high speeds.Magnetic Circuit Picture a magnet to be almost like a battery The lines of force from a magnet Circuit‐‐Picture battery.are said to originate at one pole and return to the other, just like a battery. Air is a poorconductor, both for electric and for magnetic lines of force. In order to make best use of a magnet(and our copper wire) in an alternator, we need to have the strongest possible magnetic field. Justlike copper is a good conductor of electricity, steel is a good conductor of magnetic fields. A good pp g y, g g gmagnetic circuit involves steel between the poles with a gap (the airgap) where we need to utilizethe field. In an alternator, our wires should occupy the airgap, it should be no wider thannecessary, and every other part of the magnetic circuit should be of steel.We can either use steel laminates (laminated steel reduces eddy currents) or we can havemagnets on each side of the coil(s) moving together with steel behind them. Again, look at ourvarious wind turbine experiments to see. It should be said that some of them, like the woodenalternator and the all wooden windmill have very poor magnetic circuits.
    • 24. BLADES:
    • 25. Blade Material—Wood is really an ideal material for blades. Itis very strong for its weight, easy to carve,inexpensive, and is resistant to fatiguecracking. Choose the best, straightest, mostknot‐free lumber you can find; pine andspruce are excellent. Hardwoods are generallytoo heavy Steel and aluminum blades are heavy.much too heavy and prone to fatigue cracking;sheet metal would be a poor choice, andextremely dangerous.Cast reinforced Fiberglas® blades are verystrong, and are common on commercialwindmills‐‐but the mould making processwould take longer than carving a complete setof blades from wood, and there would be littleor no gain in strength.
    • 26. Diameter--Blades that are too short attached to l d h h h da large alternator will not be able toget it moving fast enough to makegood power. Blades that are toolarge for a small alternator willoverpower and burn it up, or p p,overspeed to the point ofdestruction in high winds‐‐theresnot enough of an alternatoravailable to collect the energycoming in from the wind.
    • 27. Number of Blades-The ideal wind generator has aninfinite number of infinitely thinblades. In the real world, more bladesgive more torque, but slower speed,and most alternators need fairly goodspeed to cut in. 2 bladed designs arevery fast (and therefore perform verywell) and easy to build, but can sufferfrom a chattering phenomenon whileyawing due to imbalanced forces onthe blades. 3 bladed designs are verycommon and are usually a very goodchoice, but are harder to build than 2‐bladed designs. Going to more than 3blades results in many complications,such as material strength problems h i l h blwith very thin blades. Even one‐bladed designs with a counterweightare possible p
    • 28. Tip Speed Ratio (TSR)--This number defines how much fasterthan the windspeed the tips of yourblades are designed to travel. Yourblades will perform best at this speed,but will actually work well over a rangeof speeds. The ideal tip speed ratiodepends on rotor diameter, bladewidth, blade pitch, RPM needed by thealternator, and wind speed. Higher TSRsare better for alternators andgenerators that require high rpms‐‐butthe windspeed characteristics at yourparticular site will make a big differencealso.If in doubt, start in the middle and ,change your blade design depending onmeasured performance.
    • 29. Taper-- blade designGenerally,Generally wind generator blades arewider at the base and narrower at thetips, since the area swept by the innerportion of blades is relatively small. Thetaper also adds strength to the bladeroot where stress is highest, gives anadded boost in startup from the widerroot, and is slightly more efficient. Theideal taper can be calculated, and itvaries depending on the number ofblades and the tip speed ratio desired.Hugh Piggotts Windpower Workshop Piggott sbook and his free Blade Design Notescontain the relevant formulas. Honestly,though...if you simply take a look at apicture of a f i f functioning small‐scale wind i i ll l i dgenerators blades and estimate thetaper by the eyeball method, you willcome very close to meeting the criteria y gand have a very functional blade.
    • 30. CarvingBasic introduction t bl d d iB i i t d ti to blade design and dcarving Pitch and Twist‐‐As weve said before,a simple wind generator blade with a straight5 degree pitch down the whole length wouldgive adequate performance. There areadvantages to having a twist, though‐‐likewith taper, having more pitch at the bladeroot improves startup and efficiency and less efficiency,pitch at the tips improves highspeedperformance. The wind hits different parts ofthe moving blade s leading edge at differentangles, h l hence d i i i some t i t O of designing in twist. One four common blade designs thats right in themiddle for design parameters is to build aneven twist of 10 degrees at the root and 5degrees at the tip‐‐but the ideal solution willalso depend on your alternator cut‐in speed,efficiency and local wind patterns.
    • 31. Airfoil--There are great l h lengths that you can h hgo to for designing an airfoil...NASAhas some great information andcalculations out there on the net. Butall an airfoil needs to do is maximizelift and minimize drag. You will do fine gif you do like we did‐‐find a likelylooking airfoil cross section from aworking wind generator blade and blade,copy it. A power planer makes quickwork of carving it, and a drawknife isgreat for carving too especially with too,the deep cuts near the blade root.
    • 32. Balancing--The bladesTh bl d must b very well b l t be ll balanced t d toprevent vibration. This is more easilyaccomplished with a 2‐blade rotor than a3 bladed one. But generally, we simply usea homemade spring scale to make surethat each blade weighs exactly the same,and that each has the same center ofbalance.balance A simple balancing jig for anyrotor configuration can be made with anupright spike that sticks into a dimplepunched at the exact center of the hub.Excess material fE t i l from th h the heavy areas canbe removed quickly with a power planer.Youll also need to balance the blade inpplace on the alternator. Its weight gdistribution can be adjusted by attachinglead strips to the blade root
    • 33. Furling Systems
    • 34. Furling Systems-‐We use the term "furling system" to Wedescribe a mechanism that turns thewind generator rotor at an angle outof the wind, either horizontally orvertically, to protect the machine fromdamage during high winds. Ideally itwill keep power output levels near themaximum even when fully furled. Ourearly wind turbine designs didnt usefurling systems, and we feel fortunatethat some of them are still flying.A wind turbine that f l i also much i d bi h furls is l hmore gentle on your tower and guywires‐‐the force on an over speedingwind turbine increases as the windgets stringer.. There are a variety offurling system designs:
    • 35. Furling Tail-‐The generator i mounted off‐center Th t is t d ff thorizontallly from the yaw bearing. Thetail is also angled in this axis. The tail isalso angled in the vertical axis and axis,hinged. When the wind force back onthe rotor is strong enough to overcomethe off‐axis generator making it want to g gyaw and the angled tail trying to keep itfrom yawing, the tail folds up and turnsthe alternator away from the winddirection, f forcing the wind turbine toyaw out of the wind. When wind speedsdrops, the tail is returned to normaloperating position by gravity or springs gravity, springs.Many commercial and homemadedesigns (including ours) use this system,and it has proven to be very reliable.
    • 36. Variable Pitch--An ideal but tA id l b t extremely complicated solution l li t d l tiis to use blades which change pitchdepending on the wind speed....these alsohave the advantage of keeping poweroutput at the most efficient point for thecurrent windspeed. During low winds, theblades are pitched for best startup.In higher winds they rotate and adjust shaft winds,speed to the ideal RPMs for the generator.In extreme winds, they turn the blades evenfurther to protect the unit from damage.The problem is the complexity of making asystem work reliably...but it can be done!Large commercial wind generators use thissystem exclusively, as do antique and y y, qmodern Jacobs turbines, and some oldWinChargers.
    • 37. Tilt-Back--In these d h designs, the generator b d h bodyis hinged just behind the nacelle.When wind speed gets too high, theentire nacelle, hub and bladeassembly tilts back out of the wind tonearly vertical. As the wind slows ydown, it returns to normal horizontaloperating position by either springs,wind action on a tilted tail or a tail,counterweight. Commerical windgenerators that use this method arethe old Whisper models (from beforethe buyout), the Windstream, andmany homemade designs.
    • 38. Folding Vane--Similar to the f l tail, b the tail l h furling l but h lboom is fixed, with a hinged vaneunderneath. Used on some olderWinchargers and homemadedesigns, the disadvantage is that tailand vane are more highly stressed g yfrom wind force during furling, asthey still are sticking out there in thegale.gale
    • 39. Flexible Blades--The theory is that the bl d fl h h h h blades flexboth back toward the tower andaround their main axis, andtherefore protect themselves fromoverspeeding. It does work if thematerials and details arecorrect...for example, the bladesmust not flex back far enough to hitthe pole and they must withstand pole,flexing during cold weather too.
    • 40. Slip RingsThe power produced by the generator must be transferred down thetower to your power system. Since the actual wind generator must yawto keep pointed into the wind, the main power wires must be able tohandle this.There are 2 options...Pendant Cable Our personal experience up here is that it is much easier Cable‐‐Ourto simply use a length of flexible cable and a steel safety cable instead ofslip rings. Use the highest quality stranded, flexible cable you can findand attach it in a loose loop from the wind generator power terminals towhere your feed wire comes up the pole. Use a length of wire that allowsabout 3 or 4 wraps around the pole. Or, run the wire down the center ofthe tower pipe and let it twist inside. Our experience is that while thecord can eventually wind itself around the pole, it will also eventuallyunwind itself. Some of our models have flown for years with this kind ofsystem and required no maintenance. With a properly designed windturbine and furling system, you should hardly ever see the mill make a360 ddegree yaw. W simple use a power plug and socket at th b tt We i l l d k t t the bottom of fthe tower and unplug it once or twice a year to untwist the wire.Weve seen commercial turbines on 120 foot towers that successfully usethe pendant cable system.Make or Convert Slip Rings‐‐Slip rings can be salvaged from old caralternators and converted to wind generator use, or built from scratchusing copper pipe, PVC pipe and graphite brushes. Home PowerMagazine has had articles in the past about both methods. We havenever felt the need to use them and they make for another potentialfailure point, so we hf il i t have not experimented with it t i t d ith it.
    • 41. Shutdown Systems
    • 42. Shutdown Systems-‐This is a manual control that h l l hcompletely shuts the wind generatordown. It is not allowed to spin at all,and should be able to surviveextremely violent winds in thiscondition. It can be electrical ormechanical.Air Brakes‐‐Noisy and full of vibration,but they do work Older Wind Chargers work.used this system. Metal cups extendfrom the hub from centripetal forceduring high i dd i hi h winds, and noisily slow the d i il l hmachine down; they retract back intothe hub when the wind slows.
    • 43. Electrical Shutdown--With permanent magnet alternator machines machines,simply shorting the main AC power output leadstogether should effectively shut down the windturbine. The problem is that when the machine isspinning at high RPMs during a windstorm, theshutdown may be either impossible electrically(the turbine is performing too inefficiently forshorting the output to have any effect), or toodamaging to the alternator (the heat produced inthe stator coils b shutdown at hi h speeds turns h il by h d high dthe coils into molten slag.) Our normal method isto simply wait for a space between high windgusts to short the mill with a switch. We havesuccessfully shut down Wards turbine while it Ward swas putting 30 amps into 12vdc...numerousshutdowns at 10‐20 amps of output have causedno vibration or problems. You can use a manualswitch, or simply a shorting plug to do this. Our py gp ghomebrew deisgns have never had problems withrefusing to stop in high winds when shorted.
    • 44. Mechanical Shutdown-‐These systems physically b k the h h ll brake hwind generator, or force it out of thewind by turning the tail parallel to theblades. Even the mighty Bergey Excel10kW wind turbine has a mechanicalcrank for emergency shutdown. g yGenerally, a cable is attached to ahinged tail, with a small hand winchlocated at the bottom of the tower forthe operator.
    • 45. RegulationWith b h battery‐charging wind generators, regulation of the incoming voltage is h d l f h laccomplished by the battery bank itself, until it is fully charged. Though a PMalternator or DC generators open‐circuit voltage might be 100 volts, thebattery bank keeps the wind generator circuit voltage at its own level. Oncethe battery bank fills, system voltage will rise rapidly and something must bedone with the uneeded incoming power. gpSimply disconnecting the windmill is not an option‐‐a windmill allowed tofreewheel will quickly blow itself up from overspeed. The power must bediverted into some sort of load load.
    • 46. Turn on Some Lights!‐‐This is the oldest, simplest andmost reliable method of regulation.Problem is, you have to be there to ob e s, a e t eedo it. But by turning on house lights,heaters, etc. that more or less equalthe extra power coming in you in,prevent the batteries fromovercharging, keep a load on thewindmill and keep your systemvoltage in the normal range.
    • 47. Shunt Regulation--These systems simply sense th b ttTh t i l the battery voltage and di t power di tl f lt d divert directly fromthe batteries into heating elements (known as a dump load), thus keeping a loadon the windmill while avoiding overcharging of the batteries. The very simplestsolution is a manually thrown switch that disconnects the incoming power fromthe batteries and connects it to some heating elements...just keep in mind thevoltage requirements of the heaters must be a good match to the alternator forbraking to occur. Simple systems that divert all the incoming power at once can g p y gpbe built using Trace C‐series charge controllers or relays and voltage sensors.More complicated systems use power transistors or pulse width modulation todivert only part of the incoming power, or the entire amount, as charging needsrequire.Both Home Power Magazine and Hugh Piggotts Website have plans andschematics for building shunt regulators. Some commercial solar chargecontrollers can b set to f ll be function as d i dump l d controllers, lik the T load ll like h Trace C40 A C40.controller intended only for solar power will NOT function with a wind turbine,nor will an automotive voltage regulator.
    • 48. F.A.Q. S F A Q ’SQ.CanQ Can I just plug my wind turbine into my house wiring to help offset my electric bill?A. No! No!! No!!! I am getting this question a lot and it really scares me. You need specializedequipment like synchronous inverters and transfer switches, and a licensed electrician, tointerface a wind or solar system with your house wiring safely and legally. Do not attempt to do ityourself unless you really know what you are doing and have obtained all thenecessary equipment and permits. In some areas some or all of the work may have to be doneby a licensed electrician. Check your local codes.Q.Q Will I be able to heat my house with a wind turbine like this?A.Probably not. This wind turbine only produces a few hundred Watts peak. It probably wouldnteven do a very good job of heating one room, let alone a whole house.Q. How noisy is your wind turbine? Id like to build one, but Im afraid it might be too loud.?A.The wind turbine is not really very noisy. I do have it set up about 100 feet away from me, butit is not terribly noisy even up close. It isnt much noisier than the wind itself. Most of the time, ina stiff wind, I cant really hear the wind turbine at all over the roar of the wind through the trees.The l time I actually notice th noise fTh only ti t ll ti the i from th wind t bi i when th wind h b the i d turbine is h the i d has beenblowing hard and then suddenly drops off to almost nothing. Then I hear the whooshing of theturbine blades for a few seconds until they slow down.
    • 49. F.A.Q. S F A Q ’SQ.Q Do I really need the battery bank and charge controller? Cant I just connect my Can tinverter or other appliance directly to the wind turbine?A. The Voltage output from the wind turbine varies wildly with wind speed. You would bevery liable to damage the inverter or other appliance by running it connected directly tothe i d turbine ith t battery b k and charge controller i th system. Th l d fth wind t bi without a b tt bank d h t ll in the t The load fromthe battery bank smoothes out the Voltage to something the inverter can handle, andprovides power during periods of little or no wind.Q. Will a solar panel charge controller work for my wind turbine?A. Unlikely. Most solar panel charge controllers simply disconnect the panel(s) from thebattery(s) when full charge is achieved. This leaves the solar panels open‐circuited. This isnot a problem for solar panels. However, wind turbines need to be connected to a load atall times or they will over‐rev. When the batteries achieve full charge, the wind turbineneeds to be connected to another load, rather than open‐circuited. It may be possible tomodify a solar charge controller to do this, but it would depend on the particular controller.I cant help you with selecting a controller or making modifications.QQ. Which direction does your wind turbine spin? y pA. When looking at the turbine from the blade side, (as opposed to the tail side), theturbine spins clockwise. So the motor shaft turns clockwise. The direction of spin is notreally all that important. A DC motor will act as a generator no matter which way it isturned. The polarity on the output will just reverse if the direction is reversed.
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