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Forum Index : Windmills : standard f&p wiring usefull?
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| BBBrad Newbie  Joined: 16/02/2008 Location: Posts: 4 |
Hi, im new here and wanting yo know a couple of things. I want to be able to power a normal mains type elemnt for heating water such as in a hot water cylinder etc. I want it to be as simple as possible. No batteries etc. I know all you guys rewire the f&p to put out 12v, or 24v etc for battery charging purposes. I dont know too much about electricity but know that a standard wired f&p puts out over 100v ac, which I thought would be more suited to a mains powered element. I do know an element is a simlpe device that needs no regulation, windmill turns slow/element warm...windmill turns fast/element hot. That all said I must say ive got dozens of f&p motors of all types and am an engineer that can build a windmill of almost any size. What I want to know is what configuration of motors and how many I would need to power a hot water cylinder element. Hope this makes sense, Thanks in advance. |
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| dwyer Guru  Joined: 19/09/2005 Location: AustraliaPosts: 574 |
Hi BBBrad What size is heating element you want to use otherwise if windmill turns fast/ wrong size element will burn out is depend on the wattage/voltages that design for ?? One F&P will not heat up 240 volt /1800 watt heater. 
Dwyer the bushman |
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| BBBrad Newbie Joined: 16/02/2008 Location: Posts: 4 |
Thanks for fast reply. I would think approx 2000 to 2400 watt element. I understand one f&p wont, I can make one big windmill to turn 4 f&p's or 4 small single f&p windmills. From what ive read 4 would do the job probably. What would be the best configuration to join 4 together. Would be good to not have to rewire them also. Am I wrong in saying that the standard output voltage would be in the ball park for a 240v 2000w element? (if you could group them upto this wattage range?) Thanks again. |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5116 |
Hi BBBrad Yeah a F&P in standard trim will make over 100vac easily. Dont get zapped! A heater element as a load will react the same way as a light bulb, and not as simple as you first would think. First up the low resistance will make it difficult for the windmill to get started. See a rectifier/battery load we usually use wont draw any power from the windmill until the windmill has sped up to cut in speed, meaning the windmill gets a chance to spin up before its loaded. But a resistive load like a heater element appears as a load as soon as the windmill starts turning, and this can stall the windmill out unless there is enough wind. The other problem with heater elements, like light bulbs, is they are designed to run at a set voltage. If you go over this voltage, they will blow! What you need is a circuit that will allow the windmill to freely spin until its got enough power to drive the heater element. And you will also need some sort of over voltage protection, or regulator, to protect your heater element during wind gusts or storms. That said, its not difficult to do. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| BBBrad Newbie Joined: 16/02/2008 Location: Posts: 4 |
Thanks again. I think I read somewhere that the f&p will gett to a certain point and will not put out any more power, (even if the winds gets stronger). I was thinking of having a setup that would meet "most" of my power requirements in the most desirible conditions. So that no mater how much the wind blows it'll never blow the element. That been so I like the idea of a cutout and starter device like you've described. If it was simple enough, would be cool. I do understand the cogging issue and was going to try and build a clutch on the prop that would engage at rpms similar to a seatbelt tensioner. Thanks again. |
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| BBBrad Newbie Joined: 16/02/2008 Location: Posts: 4 |
Also if I was to run 4 f&p's together on the same mill could I help the gogging issue by slightly altering the phasing of each f&p? So they are not all lined up perfectly? |
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| KiwiJohn Guru Joined: 01/12/2005 Location: New ZealandPosts: 691 |
Hi Bbbrad, if you want to use multiple F&Ps they must be in phase if you want them to power the same load in AC. Of course you could use them out of phase if you rectify their outputs individually and your heater (resitive load) will be just as happy with DC as AC, though there may be other issues to consider. |
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GWatPE Senior Member  Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi BBBrad, How much power do you think a F&P will produce as a windmill generator? You might get a useful 300W in a blow per unit. You can use a high wattage load if you use a modulator and this regulates the mill output. The 2400W heater is about 24ohms. This would present a 416W load at 100VAC. As Gizmo has said, "not as simple as you first would think." Take care with your wiring if you go this way. cheers, Gordon. become more energy aware |
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Bryan1 Guru Joined: 22/02/2006 Location: AustraliaPosts: 1453 |
Hiya Guy's, This thought crossed my mind awhile ago but main sticking point I had was the F&P outputs wild 3 phase AC and the water heater elements are single phase. Now I don't know too much about 3 phase but to run single phase off a 3 phase supply don't you need a neutral wire ?. Now say we set the F&P up in star and brought a neutral wire out from the star point, wouldn't that let us tap a single phase from the 3 phase mill. As Glenn pointed out above regulation would be needed to get the mill started. Like I said mechancial stuff is my game not electrical and this is just a hair-brained thought that might hold water or go down like the titanic. Cheers Bryan |
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Gill Senior Member Joined: 11/11/2006 Location: AustraliaPosts: 669 |
Bryan1, In keeping this simple and theoretical, connect 3 heating elements to the phase wires. They could be in the same arrangement as the generator, alternatively, say if the voltage was too high, you could connect the generator in Delta and the heating elements in Star. Conversely if the voltage were to be too low, connect the gen in Star and the elements in Delta. All those wonderful choices.........  was working fine... til the smoke got out. Cheers Gill _Cairns, FNQ |
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| Gill Senior Member Joined: 11/11/2006 Location: AustraliaPosts: 669 |
BBBrad, G'day mate, welcome aboard the forum. Bit of a sttttutter you've got there??!! When you asked, "If I was to run 4 f&p's together on the same mill" etc., the answer is 'yes', you will reduce cogging by staggering the pole alignment between each stator. However this is not so easy to achieve and if I remember correctly, it was reported by the person who did it that that the adjustment altered after a time. I don't see how this would be so but is worth a mention. Also adjusting for reduced cogging in this way, is, in effect, the exact opposite of synchronising the 4 AC outputs. Therefor to reduce cogging in this way would necessitate rectifying to DC before powering your heating element, unless of course you go to 12 elements.  was working fine... til the smoke got out. Cheers Gill _Cairns, FNQ |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi all, A question for the aerodymamics people. What is the difference in loading for a turbine exhibiting a TSR < 1 and one with a TSR > 1? My reasoning is that a turbine with TSR < 1 should have no problem with startup, so the resistive load to heat water would work with a VAWT. The load resistance would load the mill with a squared relationship to mill output volts. A HAWT is better suited to charging batteries as most utilize a TSR > 1 and so the mill usually runs unloaded to the cut in voltage. A resistive load would need to be modulated in some way. cheers, Gordon. become more energy aware |
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