Table Of Content

Brakecirum PM-Alternstor Winds Plum, UK 1999 Hngh Piggott 1998, : Brakedrum “permanent magnet, a alternator Ford Transit Brakedrum permanent magnet alternator wind turbine plans - first concocted in 1993 Contents: PAGE L Why do it like this at all ? The story, how ( got here. 5. General notes More preampie 6. Dismantling the back axle - sown to work 8. Dismantling the electric motor 9. Fitting Magnets to the brake drum 10. . Winding the colis 12. Connecting up the coils 15 Making the propeller ~~" . 22. Putting it together with a tail etc, 27.. Resource list fourth editian Hugh Piggott . Scorai; raig Wind Electric 1998 Rose shire, Soctiand TELFAX (01854) 633. 238 Casta A FORD TRAMSIT HUB AMD BRAXE DZUM TO SUILD A WIND TURBINE CEXERATOR. wait 00 Te L have buen making windasil from werep aatersale for twenty years. 7 Onl and I Like recycling, Tha biggest headache hes oluays been to find sullable generator. tov epesd, be efficient (oct Mwsterul of pever?, ond aleo be relishie and Mffordable. 4 tough epac. Venlele dynsnos and elternatora vare the obvious first choice, but they need rather high speed <rpm and pre ine(ficlest. 1 learned to revind Luce altercatera; se thay vould uock at lov rpm, but the af(terency vent froe tad lo Wore, 0 mont of the anergy caught from the wind wos vested ‘ing up the alternatar, The bast bet turned out to be djnanae fram buses oF Jeeps, 4 low apeed 24 valt dyneno can te alaply converted to a very lov speed i2 volt dyauso, and Thece heavy o14 machinse are rugged, efficient and cheap, T have described hou tor mak thew into windallle to my bocklet *Screpyard indpowsr Realledee’, (iret published 1» (982 tupdated 1382). (NOW OUt Of print) ‘There are many euccaceful vindst lls tm operation ba bat I have become painfully euere of the ahartcout ag: the performance in Sight winds, Hare in the reseon uby: ALL generatore require wagostiom they vorr by dragging colle of Mire through @ magnetic field Yahicle dynance and alternatore use electomagiate, ond (beta need aboot 4D vette of power AT ALL THES. Sa the Firat 40 watts of power you ganarate fe used up unargising the {aid catle, and only woen tbs vind te etrenger do you tae an actusl “prafit™, in terme of charging tha battery. Old dyrance era sleo harder “and herdar 79 sbteln in good Coaditien, end (herd are saSatanence probless with the Drushen on these dynano ‘The vorat thing = ‘The tect type of generator for = umell vind turbine tau purpose busit, paracoent eegnet alternator (pea). This requires no field colle to ftuergiea, and hee ao Brushes to coure probless, There are scrép parasnent ‘Michines which can pa Usefel, woch be Compuler tepe drive sotora, wetvoe ote, but I have found no -ralieble soures, Vuying paraaneat magnet machicary' peu ie expensive, sad I pretar'to recyela, 00 T Started making alternators built on voeel Dearing. Key Firat tespt 18 datetind an “Serapyerd Minapéver” web a rather leboriove, unlded fabrication of etent asece, Ragnets Blued on the fucee of tba steal disc Fotpiad paat colle eat in & Te design Used by Marlee for their Rutland ied -torbinas. Lt worked vary Fallah3y, but felt thal tt hed bean (D0 much Rensle to Justify bulging enother. - But-over the years;-quite-a few-people have. built these, using the plans in 'Scrapyard" and | hope to produce a new, united set of plans for both approaches, one day. Snail oncefean vind turbines auch a6 the Shlaper ond Bergey mectinee Une 8 Seterent geonstry for their poe. The Sagnece are glued ter tha inner eurface Dien cylinder tetael tbe) undeh fotetear, “The colle which produce the Gutpur are wrung one eteticemy core of Taeinated tran neteriai, with elote in Jia outer turtece far the colle te fil Jntor tine etetionsry bit with the cotle Ao called the cistor.) Tt esned Tone thet e such etepler theel-hut pro could-be Bulle weing brake grom rether —— then tae! @iecer end Vollocing chic AMERCAW “STIEE BAR shcraten etyiec “Long wheelers Ford GASESTOA A“GRANL. -” Pacuet Gronett vene heve Big brake dros oo the Sera. beet axle, and excellent. bearings, Clune, Daa stNEt. “Gus 109 Y'bn0 17 BuceKS, GUE. LODE. Finding suitable magnets uae nat a problon, Haunt Electronics tn - A}rminghom geve the best quote, although I could have got oraller quentlites from Kegnet Appiiceiiona, at tuice the unit price, The anternal, Utemeter of the brake detm 4a 10 inches (25énm), The Length 12 2h inches Ginn). I chose wagnel blocks Gt by 32 mm with thickness ZOnm, (negrelieed thraugh the thickness), Twenty magnets con be (itted around the inner face of the run, bringing the internal bore dew 16, shout 212m. the tg pronten vee finding Lontnate (DEAL SRORE GK LArwNOTIES | mlerttr’tor the core ot the stators to carry the coils the core hac ite SUT FOR Coes Save tres thie Laninatee of sett dren Hacked Inte eelld block “You cen sce Theslan treustoreer cores: or yneeo Brecturen If you veed eolid fromthe Shonging mignevie ffelde would ve! up Shetater esay corrente in the von, out the lequer between the laninetes preventa bia. ] waned o core which Thttea clove up to te magnetar with only a spell vir gop. end clove to-csrry he cotter ev in the spertean deeign, & toni air gop eliove the sexiave tegnetic fHeld strength, But the Gieneter of Lesinates nateriel T nseded Soc much Bigger, than stengora sizer in crap dynaube ete, and to have it porpese pede would have added over 2 Rinred poones tthe oct of each miternetor Tee ke” 5 Se Beowincs Se: DENTE For @ UNLIb I alacet abandoned the uncle idee. 1 could dee no way to eoke the stator at low cout, Then Gorcon Hrcven of Preven Wind Tu=bines encouraged me to try 0 different. tack ‘ee voy £ did 4¢ tm the ang wan uming Laningtes trom a very ordinary big Qephase, 5 heres elactric motor, The Inainaten ers the:tureng way out", With lots on the toner bors, and an aiacat, mopth out eurfaca,divaster & anche €G03aa). Sethar than placing the colle T glues thea'on the outer face ofthe Laninated core, in thy 4 Sam gap ‘between core and magnet fac fe a rather large Held, end the £1 of at ‘cheop’ (trom 4 perep sotor) feeubling elternater does vor In fact the alternator was quite a success. -for-its weight,it is not as efficient as-an alternator with-the-right sort-of laminations and a smaller airgap, but it does have some advantages. For one thing, this sort cf lamination is much easier to find. Also, the alternator starts up more easily in light winds than it would if the airgap were narrow. Machines with small airgaps have imuch higher Magnetic drag, which holds the windmill back from starting up in light winds. I glued the coils to the outside of the laminations with epoxy resin. Ineeded a very thin layer of coils, so | used a g-clamp to press them down, onto the lams, The wooden former shown is easily made by carving a hollow in the wood with an internal radius of 104m, From past experience, the commonest problem with permanent magnet alternators is that the magnets start to rub the stator, so | allowed plenty of clearance (around 2mm). So only Just over half of the ‘airgap is filled with coils. You could get more power by making the coils thicker, but at the cost of lower reliability. | have never had a problem with the magnets hitting this stator, even when the bearings were quite slack. The resulting windmill has been one of the best | ever built, and | immediately set to work and prepared plans so others cauld do the same. | actually built it for the low windspeeds of the Glastonbury Festival site in 1993, where it proved ta be as good as the Marlec fm1800 wind turbine in low winds. After the Festival, | put it up on a hilltop site near my home, powering a neighbour's house. Here it had the chance to prove itself as a high windspeed survivor. The furling tall system protects it against overspeed. At first we set the tail up to limit the output to 300 watts, but after a couple of trouble free years | added more weight to it, so my neighbour gets 500 watts (well actually rather less, as nearly half is lost in the cable to the house). Here is some data for the altemator (connected ‘star’, for 24 volts): Cut-in rpm = 200rpmll Internai resistance 4 ohms. 3 amps at 30 volts (90 watts) at 320 rpm 9 amps at 42 volts (378watts) at 600 rpm. See page 28 for more details on amps and volts. The technically minded reader will have sussed out that there will be quite some heat generated in the windings when the alternator is putting out 9 amps. In fact the loss will be about 36Qwatts, so the alternator is only about 50% efficient at this point. This is not wonderful efficiency, but the important thing is to.be efficient in light winds, when power is searce (and this alternator certainly is that). In higher winds, there is often power to spare, and also plenty of cooling to prevent the windings from burning out! To milk the best output from the alternator, you should ideally load it with only a small current and use higher voltage in higher winds. The Marlec fm1800 wind turbine has @ special controller which does this, {part of the reason why this windmill is so expensive). One solution would be to use ster connection in low winds, and change to delta in high winds. Resistive loads (heaters) will work with better efficiency from the alternator than baltery loads because their voltage will vary. But this is not a crucial issue, and In fact you will have a very good windmill even if you ignore the sbove considerations. SEXBRAL HOTES i abowld be very surprived 1£ anyone follows thooa planm exsctly, although this coursa of action wosld certainly give good resulta. Tn practios, 1t ie most likely that 7 a) the parte which are obtained will vary slightly in eize and shaps from those suggested . b) individuals will have their ova ideas tor «iapler or better waye to euit thatr own ekille and resourc: For axample, I have mada mich uae of alactric welding, but for eome it will be aaaier to bolt pieces of steel together and so avoid welding, BLADES I prafer to make blades from waod, but they can also be made from gincafibre and resin, or even from matol. Metal blades wil? tend to Suffer from fatigue, and this danger ubovld ‘be recoguieed. dordon Proven hag a ting technique for making bladae trom polypropylene ab Tam net qualified to describe this properly; ‘have used a 3-bladed propeller for this windmill, becuase they run more smoothly than 2 bladers and faster than 4 or more blades would. You could use a larger, 2-bladed propeller istead, The pitch of the blades would need to be finer (flatter) in this case, You could increase the diameter from 2.1m (7°) to 2.7m{9') using a higher ‘tip speed ratio’ (see my book ‘Windpower Workshop’). SPEEDING The alternator can be run through a belt-drive to obtain higher spaed, and ao more power, from the sama mohine, if thie ts considered worthwhile. Balt’ ariva or other gearing 4s not. only more work to meke, but will introduce friction, which may make starting Aifficult in Light winds The windaill described here cute in at a very low windepeed, for battery charging applications, where a reliable, slow:oharge. im ast deairable. Tt ia at ite moet efficient when 1t oute in, but im fairly inefficieat by tha tine it delivera 300 vatte, directly driven by = propallar, and wired aG deccribed hare, for low epsed cut-in, Higher ovtpute could de obtained with good arfioiency by running it at higher speed, and either reviring the pile in peraliel groupe, oF operating at higher voltage, Thera dm a trade-off between. peed. and Power which you can use: Bore apead allows the alternator. to handle Hore power, tut aleo bringe more problaiw with soles, weer, fatigue And vibration. A better mpproach to getting sore paver would be to eo a larger bratedrum or fabricate sometbing with larger diameter- ‘nil up to you, but I am available to give advice on the phous or or fax enquiries cerrive airs There ia 4 list of suppliers at the end of the documat, ta help you finds the bite you need, If you find ohesper sources (I'am mure they exint) parbape you would let me know, apd I mhall pase the information Gn to othere, If there de anything you really ommnat gat hold of Clomiaatas my bee problem) then I my be able to help out. The Ford 3/4 ton truck brakedrum can be used with inch thick mangets and 9.75 inch laminations. DISMASTLING TRE BACK Axi Ynat you nead tan big brate drum from « Ford transit long wheel bese vas or similar. There iu a Bedford vith the came size brake drum, si hare will probably be other makes, Pront vheel hube Umuelly inva, digc brakea thane daye and ou ere mot suitable for this design of alsarnater. Tou need “fully floating" bearinge on the bub, ts the mud iat be eupported by two Dearing races, avon after the Bali hart te Femived, Im tha case of the traneit, there ere tuo tapered-roller beartage. Rear Axle Halfshaft {insice) shown in black ifferential Gearbox te Brakedrum Americans may find the Ford Must be deep as shown 3/4 ton truck brakedrum to accommodate the windings useful, although the internal diam is 12 Inches. ‘The firat etep is to remove the balf enaft, which carrian the drive from the gearbox out to the hub, Thie ie done by removing the eix mil aute assr the oeatra of the hub; end simply pulling the clrovier Flange ubigh te actually the ead ef the mart, jaxt you saad to remove: the outer basring race, which im retained by eo large thi oute. The outer nut (dich hue bean reveeled by removing the half abaft) 10 looked by # tab bent ovtward from a weber babdnd the nut, Knock this tab backwards With a screwdriver or puoch, Grives by a hammer, 20 thet the nut ond turn, The aut de undooe Centiclockwiaa) by placing a chimal against » corzer, and driving At eround with = Aamear, Lift out the weaker, and remove the emcand aut da the ease way, Now the bearing rece is free ta come out, but it may act wieb ta, The eaeieet wey I Know to pareusde 1t t= to refit the half shaft teck-to-droct <eticking out, not in) and tighten tes oF three nuts, Pulling and waggling the shaft should we the Dearing, When it comm cut, keap if clean. [¢ wil] need $0 be wmsied fn petrol ond vapacked with grease Cn acdaratign? bafore refitting. Brakedrum. Section through hub, showing_ tapered roller bearings Axle tube. “~~ Flange supporting brake back-plate How the wiole hub and broredrum can be removed from the axle, but it Eay ati! be retained ty the brake shoes and the seals. Ensure that fhe handbrake cablu 1¢ releseed, Keep waggling and pulling the halt Ghaft. Some hanner bieva eay alec be needed to relenus the brakes. The brake parta con e remuved as @ whole by undoing-the four muta which retain the brace beck plate ta the azie. These nay need Penetrating O11, ar vven sce heating, af they Will probably be forroded, A piece vf piye oo the end of the socket wrench will give you more leverage innd you may aluc beud your weeach! >, Again, some Xanmer blows may help to crack the rust and let in tha easing ofl Having removed the Liake parte, KnOck out the eorave which hela then with ® hamser. The ceal.on the dnnar nnd of tha hub can be removed from the Nb ubtog B baneet and eorevdriver to prise t out. Jiaybe there is a more Sophisticated method but thie does work ok. cake care not to damage The inner bearing rece. The Purpose of this Geal was to keep the of} (whieh come from the geacsoy ta lubricate the bearings) cut of the brakes. The seal causee s lot of friction, and you do not nead it You can saw off tho azie tube wherever you want, veing © eherp heckeaw blade, in = few minutes. It ig not that bard to do! Take it slowly, Use the full length of the blade, oud pey attention to keeping it Square. T evt it osf quite close to the oad, but 17 you plan to bolt he windmill together ratuer than weld it you can leave the flat bracket {wich noraally metu the leaf eprings? ettached tothe end you are using, For s usil fee, the scrap merchant will probably cut TP off with omy-scetylene et the point of sale, end this would cave you from transperting the Incredibly heavy axle home at all. owe,