PMA info required

[sweetwind]

Hi

Being a newbie, i might ask some stupid queries, please forgive me.

I have gone thru the document on Axial Flux PMA howto. According to it, i bought the Neo Magnets (2x2x1) and yet to buy the Copper wires/cables. Which size i have to buy , can i go for #27, if i use this coil, howmany windings i have to and what size i need to wind it(like four inch big circles)?, i am planning to use it in 250+ rpm. will #27 withstand?, can any one suggest me pls

1. 100RPM will produce 600watts, 600Watts means 600Watts/hr is it?
   
2. is there a way i can produce it as AC instead of DC output and connect it tomy home without any Inverting device?,
   
3. 15 coils and 20 magnets will this be sufficient coils?
   
4. What could be the Gap between Stator and Rotor?
   
   

thanks in advance

SW

go Green

[Flux]

Being a newbie I will be kind to you but it may have been better to do more studying and ask more questions before buying magnets. Don't buy any wire at this stage.

"100RPM will produce 600watts, 600Watts means 600Watts/hr is it? "

This will need a big turbine and your little magnets won't go far towards it. Yo mention no blade diameter or likely wind speed, both will have to be larger than you think . It will get you 600Watt hrs if you can keep it producing the 600W for an hour.

"is there a way i can produce it as AC instead of DC output and connect it tomy home without any Inverting device?,"

In theory yes but you won't manage it. You will never have enough consistent wind and you will never control the thing with your ability. In reality you will not power a home directly with wind power without some intermediate storage means. That means batteries or using the grid as storage with a grid tie inverter.

"15 coils and 20 magnets will this be sufficient coils? "

Sufficient for what, what is the price of cheese?

"What could be the Gap between Stator and Rotor? "

Could be anything depending on the answers to all the other questions. Normally you make it as small as you can consistent with mechanical requirements that they never rub one another. To go larger reduces output for a given volume of magnet.

Sorry this has answered very little but you have asked nothing much that can be answered. It may be wise to spend a little money on some basic books such as one of Hugh Piggots and get a basic idea of what is reasonably possible with small wind power.

First thing to consider is your wind potential, if you have useful wind then you need to decide how big a machine you would need to supply your needs and then you can start thinking about whether it is practical. If the wind is good and your requirements small then you may be able to do something. You may eventually find it may not even be practical or you may only be able to supply some of your load and use wind as energy saving.

Flux

[David HK]

You write that your magnets are 2 x 2 x 1. Can you clarify if your measuring system is in Imperial (inches) or Metric.

David HK

[sweetwind]

Thanks Dear flux, yes i too imagined it is going to be big turbine, i went thru the document(http://www.sparweb.ca/Forum/AXIAL_FLUX_HowItWorks.pdf) and thought of trying this at VAWT, not wind mill mounted on a pole. so i am not sure of the blade size. VAWT Dia will be 9ft size approximately.

is this good start to tie up with?

[sweetwind]

Sorry David, i missed the measuring system in my posting,  it is

2x2x1 inch's

[spinningmagnets]

VAWTs are typically mounted near the ground. Sadly, the wind is usually very poor there. VAWTs can be fun and relatively inexpensive to build, and PMAs can be fairly pricey to make correctly.

You might consider making the VAWT first. Then attach a dummy load (a spinning paddle in a bucket of water?) and then data-logging the RPM's throughout the course of a few days.

Might I suggest a 2:1 sprocket set from a bicycle to double the RPM's of the output shaft? If you could find a small stepper motor from an old large office copier, it could be configured to charge up flashlight batteries.

If your data logging showed enough RPM's frequently enough, you could series the 1-1/2V batteries to charge at 3V or possibly even 6V.

Either way the VAWT must be big, and the generator small, and you will only get low power on the rare occasions there is enough wind to run it. Just some thoughts...

[electrondady1]

sweetwind,

 you have purchased your magnets prematurely.

if i understand you correctly you have 20 2"x 2"x 1" magnets

can you tell us if they neo magnets or ceramic/ferrite

do you know what grade they are?

if they are neo magnets

you will need extra thick steel rotors perhaps 1/2" thick

you would need two steel rotors approximately 29.47" in dia.

one for the magnets and one for a flux return path.

because you have deviated from known configurations

you must experiment on a basic level with regards to

wire gauge and coil turn count.

if you are prepared to do this then you can build a powerful alternator .

the next stage is matching that alternator with what ever vertical design you build

i think this is where most first time builders falter.

with out knowing what rpm your turbine turns.

and without knowing knowing the torque requirements of your alternator

it may be most expedient to build your devise with a pulley system to separate the alternator from the mill and allow them to operate at different rpm.

if you can afford it , would it be possible to return these magnets

or set them aside until you have gained better  understanding.

most of the designs you will find on this site have evolved through trial and error.

much knowledge has been gained from the experience of other.

[SparWeb]

Hi SW, and welcome to the board.

Thanks for reading my little paper, glad you liked it.  I'm afraid I didn't really give enough specifics to actually design one, in what I wrote.  It is possible to sort-of size one up with some math, but before you size the PM alternator, you would try to define the size of the system, and that would define the size of the wind rotor to turn it, which then sets parameters that the PMA has to match....  You see how there's a chain of events here.  

There are several other good resources you can find on this board to learn more about the specifics of sizing up the PMA.

If you want to start with a VAWT, then maybe just start experimenting with them, figure out if you can get some useful work out of one, and then build a PMA that can produce power under those conditions.

Fair warning: it can be very hard to get a useful amount of power from a VAWT.

[sweetwind]

Thanks a ton spinningmagnets,electrondady1 and Steven Fahey for guidance towards positive approach

Its Neo Magnets(n38) electronday1,

"you will need extra thick steel rotors perhaps 1/2" thick

you would need two steel rotors approximately 29.47" in dia.

one for the magnets and one for a flux return path.

..."  && "with out knowing what rpm your turbine turns.

and without knowing knowing the torque requirements of your alternator"

Thanks for this guidance, regarding the dia 29.47", i thought of using bicycle wheels initially and connect it to small to double the RPM(thanks spinningmagnets '2:1 sprocket set from a bicycle to double the RPM's of the output shaft'), and the planned rotor and stator size is 12 inch's dia approximately,

as per Steve's warning, yes i need to admit what kind of mistake i am doing, but the limitations infront of me made me to go behind VAWT, since i am living in an apartment with big balcony having sufficient amount of wind (10kmph on an average)

Now i will use my mounted solar panels to redirect the wind towards VAWT and try to concentrate(is it a correct term) the wind towards VAWT

[sweetwind]

Did i make any wrong comments? if so pls forgive me, but i am desparate to do this, Since already i started living in sustainable way, i would love to enforce these things in my life. Can't invest much on Solar Panel's too.

[Airstream]

"redirect the wind" is an automatic time out, either you have the wind or you don't.

[sweetwind]

Got it,

still i will keep trying and update it here, if someone can suggest me a better option, yes it will be helpful, else i have to learn on my own wish me the best

Guru's

[wdyasq]

I don't know of a pill that can be taken nor a shot administered that will install knowledge.

Somewhere in a partial education in math, one is told problems with:

One variable can be solved.

Two variables can be solved.

Three variables can be solved but it gets interesting.

Four variables is a mess to solve, if possible.

Five variables ..... forget it.

With two or more variables one can get 'sets' of correct answers.

With wind we have the wind, the power varies with the cube of the wind speed. We have magnetic flux the power of which varies at the square root of the distance. We have blades that vary with a bunch of things. We have coils of wire. Although I'm sure I have missed a factor or two, there is also builder's craftsmanship.

As you have limited the folks on the board to what the variables are ..... I am surprised you got as many answers as you did .....

Good luck and start with a 'cookbook' like build and you will learn a lot.

Ron

[sweetwind]

thanks ron, you made it clear about my communication error, will not do this mistake henceforth

[SparWeb]

...since i am living in an apartment with big balcony ...

As a reality check, try taking the depth of your balcony, the height to your upper neighbour, and multiplying them together as a total surface area of airflow available to you.  This area, multiplied by half of the density of air, times the wind speed cubed, times 59%, is the usable kinetic energy of the wind passing by your apartment balcony.  If your VAWT catches half of that energy (optimistic) and the electrical generator converts half of that energy (plausible) then you have the total electrical power that you can expect to capture.

At 10 mph, I come up with about 25 watts.

[sweetwind]

1. Fine, after a gap of 15 day's the design is up and running in slow wind (60 rpm... is that too low?) though the wind is not stable.
   
2. 
   
   

in rotor, i used the speaker magnets (12 no's of circular discs which is 2"), organised them N-S-N-S. is that fine?

in Stator, i used 1.698g copper wires (73 windings 9 coils connected in series.). The gap between the rotor and stator is 18mm. will this be okay team?

is that okay team?

 

[sweetwind]

here is the images link, sorry first time i am updating the photo,

[SparWeb]

I don't really know if it's okay or not, but now that you've built it, do YOU think it's okay?

Do you have any means of measuring what it produces?  

[sweetwind]

>>Do you have any means of measuring what it produces?

i guess it does, my idea here is how to tune it up and produce a reasonable amount of current it can, is it wrong? . I tried my level best to play with it,

if i am wrong pls point it out, so that i can correct it.

[sweetwind]

thanks a ton to hugh pigott's documents, now i could see 26watts with 60rpm of two discs. since i couldnt accomplish good wind support i used my solar panel (15w) to power two CPU cooling fan's, so in day hours i could see its working..

Thanks for many kind hearted who gave me support..

[sweetwind]

thanks a ton to hugh pigott's documents, now i could see 26watts with 60rpm of two discs. since i couldnt accomplish good wind support i used my solar panel (15w) to power two CPU cooling fan's, so in day hours i could see its working..

Thanks for many kind hearted who gave me support..