Iron core stator from ebay

[Hilltopgrange]

Hi all

        I was recently perusing ebay as you do looking for a bargain, well heres what I found  http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&ih=012&sspagename=STRK%3AMEWA%3AIT&viewi



tem=&item=220126126826&rd=1&rd=1

The seller described it as" CIRCULAR TRANSFORMER /BRAND NEW UNKNOWN USE" from the pic I could see it was a 3 phase stator of some sorts! So as I had purchased from this seller before I contacted him direct and worked out a deal for 2 of them at the ridiculous price of £60 ($120 USD) inc delivery to N. Ireland cheap as chips as they say. That was last week , DHL arrived with them today

The stators are ex UK military clearance and have never been fitted, but I have no idea of the original use. There was a label on one with the following details

PM Stator

Part No / DRG No  A 789113

W0505530

Ref No X2-6115-99-241-2451

09 May 1988

I did a Google search with these details but without any joy

So for some detail, I have made a few measurements and exposed the coil connections etc  

3 phase 18 coils with 6 per phase overlapping

Coils are wound 2 in hand of 1.2mm dia and occupy a slot area of 9x10mm

Im unable to count the turns yet with the varnish but I would guess at about 40-50 per coil

The outside dia of the stator lams is 285mm (11 1/4in)

The inside dia is 165mm (6 1/2in)

 The depth of the lams is 35mm (1 3/8in)

Coil legs length are about 65mm (2 1/2in)

The lams have 36 slots with a winding space of 9x10mm inside the insulation









This shows the 3 phases marked with colour

So here is the plan so far (but remember none of this is set in stone/resin yet!)

I want to build two new 48v wind turbines with these stators to add to the three I have flying.

I have worked out the most of the mechanical side of mounting the stator and rotor which is a little different to the norm for this type of stator. Rather than have it in a case as with a motor it will be secured with stainless fittings in a similar manor to the normal axial flux design but radial. I will post more on this later as it happens. A mechanical brake will be included similar to the one in my files and is based on a car brake drum. The mag rotor will be scratch built and machined to suit.

I have a bucket full (58) of 2x1x1/2 N50s or maybe N48s, cant remember? so I want to use them. I have worked out that I can fit 16 of them around a rotor and leave a 1.5 -2mm air gap with the stator. The magnets will be glued with epoxy but I would also like to drill and countersink them for a stainless set screw or maybe 2 in each tapped into the steel rotor. I seen this system used by sir Zubbly and it looks very secure. My main concern so far with this is the magnets are about 16mm (5/8in) wider than the stator but still within the coil legs as in the pic below. Will this mater? Should I trim the mags? Or should I just leave them centred and see what happens I can always trim them later if need be.

I have read a lot about skewing the mags or the lams from old postings, but as I am limited to the 2x1x1/2 mags I think It would be better to skew the lams. The lams have 36 slots so I think the agreed skew is 10 deg again this is taken from Zubblys 3 part how2! The stator lams are secured with 12 rivets and it should be a straight forward job to skew them! I've heard that before lol. So this means I will be rewinding as well..more fun? But I will follow the one turn test winding and try to work it out from there, there will be more on this when the time comes I think help will be needed with the maths!

Problems I foresee are

Matching the prop size to the alt as there will be no way to adjust the air gap! So blade size will be critical to avoid stall

Rotor bearings must have no play to maintain the small air gap!

A couple of questions

The stator will be exposed to the weather would powder coating it be an option to protect against rust? I can get this done for couple of beers!

Is there a way to guesstimate the blade size and possible output for this project to see if it is going to be a worthwhile job? I know it's a lot to ask but Just a ballpark guess would suffice at this stage. I was going to build a 12ft Hugh Piggott...I might build it as well lol

Has anyone got a source for the insulation in the slots, I cant travel any distance due to health problems so I need to order online, or if anyone has a couple of meters to spare I will gladly purchase it? and pay shipping etc via Paypal

Two new turbines means two new towers as well! The wife will just love that..... I think I may go and find a present for her as well and pick the moment to tell her?

I wonder would she like a couple of rolls of magnet wire???

So there it is so far, am I headed in the right direction with this?

Does it sound doable or have I messed up somewhere?

Does it make sense! Or am I talking dribble!!

Sorry if this is a bit long winded or disjointed but I have tried to include all the info I can but if I have missed something just let me know!

As always any ideas good or bad are very welcome its better to get wrong at this stage when its easy to change the design!

Many thanks to all

Russell

[coldspot]

Hi !!!

Great fun, building from what you get/find!!!

" would also like to drill and countersink them for a stainless set screw or maybe 2 in each tapped into the steel rotor. I seen this system used by sir Zubbly and it looks very secure."

I'm pretty sure he bought them pre-drilled, dilling them without building up any heat would be a do-able but messy job!!(Heat would de-magnatize them).

"magnets are about 16mm (5/8in) wider than the stator"

I'm pretty sure thats OK, My 2 HP conversions with 8 each NTL 29's hang out the edge of the coils but should be OK.

MY

$0.02

[Ungrounded Lightning Rod]

Don't even think about drilling a pre-magnetized high-strength magnet.

They have to be machined while they're unmagnetized or the magnetic forces will disintegrate them.  Then you have to magnetize them, which (for neos) requires serious special equipment.  They also need to be plated or coated to protect them from corrosion.

Not only that, you might set the neodymium on fire.  It burns somewhat like magnesium but the fumes and ash are very toxic.

The ones with ready-made holes were originally custom-built for one of our posters (I think it was Zubbly) and are now available generally.

[RP]

You might consider making iron pole shoes to go on top of your magnets.  These could then have holes to screw them down with stainless bolts thus securing the magnets.

Additionally the shoes could be shaped to draw the flux lines in from the unused ends of the magnets back to the stator (I think) and also be curved to match the curvature of the stator.  For that matter, they may help with skewing if you want to use the existing windings.

[Flux]

I think I would be tempted to use incremental magnet spacing with the stator as it is rather than destroy it and start from scratch with a skew. I would certainly try to get some figures with the original stator before destroying the winding. You could find out a lot of information on prospective power out with the original winding loaded at whatever voltage it turns out to give. You could probably series parallel connect it and use it as it is.

I wouldn't use pole shoes and No way would I attempt to drill the magnets. Use epoxy for trial magnet placing and when you have the spacing near enough for fairly low cog you can add a stainless band of thin sheet or thin wire over the magnets. I wouldn't be too worried about increasing the air gap a bit to achieve this ( less cogging and lower iron loss with a bit wider gap).

You are in a high wind area so a bit of cog will not be a big issue. Aim to optimise these for the higher winds and rely on the axials for the low wind days when the iron core machines will not be at their best.

Flux

[TomW]

UGL;



Don't even think about drilling a pre-magnetized high-strength magnet.

Be sure you don't tell Zubbly he can't drill NEO magnets. He will have to go back and undrill his then.

I remember him either drilling them or countersinking [maybe both], but forget the details. Mostly remember it because he had magnetic dust everywhere.

I never tried so I will refrain from dispensing advice. Maybe Zubbly will jump in and share his experience.

Cheers.

TomW

[phil b]

I have drilled the 2 X 1 X 1/2 neo magnets I got from our hosts. It can be done, but was not easy. I used machine shop type coolant on the first few, and then tried thread cutting oil as an alternative.

In both cases, it took 2 hours per magnet with very slow drilling and frequent stops to clean the Zubbly's 'majic dust' from the carbide bit. My tool steel bits dulled quickly.

When the magnet got warm, it started sparking! It smelled something like burning gunpowder. Remember, this is compressed powder, not a solid metal block.

The holes also rust really bad without being coated. Once the rust starts, it's hard to keep it from spreading throughout the magnet. Then you have a block of rust that will stick to everything but can't be glued to your rotor.

Maybe my proceedure was wrong, but I won't do it again. Zubbly may have different thoughts though.

Phil

[Hilltopgrange]

Hi coldspot,

           Thanks for the reply. I love junk!! and it is just as well as I seem to gather it at an alarming rate! but I always find a use for it.

There seems to be a few opinions on drilling the neos? I seem to remember a post about this and they used a glass cutting bit and plenty of lube, it might have been zubbly but im not sure. I think a few tests are called for on a few spares I have... More fun

Thanks again

Russell

[Hilltopgrange]

I think a few cautious tests are called for. I think I will probably go with the stainless option that flux has sugested but thanks for the warning.

Russell

[Hilltopgrange]

Thanks for the response

                       I think with the first of these I will try and keep it simple but I might try this on the second one or maybe skew the lams.

Thanks again

Russell

[vawtman]

 I agree with the no drilling guys.

 Ive spun a motor over 1000rpms with mags adhered with jb weld.None flew off and were easy to remove.Would use a better product for a permanent design though.

 If moisture gets between your skrewed down mag and the rotor,bad things will happen over time in my opinion.

 Mark

[Hilltopgrange]

Hi Flux

       I seem to have opened a can of worms with the drilling issue!

I think I will take your advice though and go with a slightly larger air gap and a stainless band along with the epoxy.

       For this first one I will leave the lams and winding as is as you suggest until I do some more tests and get some figures to play with and then take it from there. It would sure save a lot of work if it works out.

Thanks for your input!

Russell

 

[vawtman]

Hmmm

 It looks like 1ph is a typical 1-4 12pl slot arrangement.Lost by whats happening after that.

 Zubbly any thoughts?

[vawtman]

Darn eyes the phase paper blended into the background.Im o.k now.

[Hilltopgrange]

Hi Guys it has been a while since I posted on progress with the stators I got from ebay so here is what I have managed to do so far

As a quick reminder  

3 phase 18 coils with 6 per phase overlapping

Coils are wound 2 in hand of 1.2mm dia and occupy a slot area of 9x10mm

Im unable to count the turns yet with the varnish but I would guess at about 40-50 per coil

The outside dia of the stator lams is 285mm (11 1/4in)

The inside dia is 165mm (6 1/2in)

 The depth of the lams is 35mm (1 3/8in)

Coil legs length are about 65mm (2 1/2in)

The lams have 36 slots

I have made up a rotor and fitted 12 neos n50 2 x 1 x 1/2 the mags are only fitted temporary with duct tape just to get some figures. (I will post more detail of the construction etc later)

Maths is not my strong point so please forgive me if I have gone wrong

I bolted the stator to section of H beam and secured it to the bench so that I could drive it with my lathe. The lathe is a bit of an antique so there is no fancy speed control etc but after a bit of fiddling about with pulleys and a long v belt I have managed to drive it 1-1 and change speed with the gearbox and belt. The speed was measured with a digital tacho so should be close but I have also noted the frequency as well.  All tests where without load and the meter was connected between the star(coil ends)  and 1 phase (start) Im not sure if this was the correct way to do it but no doubt someone will put me right!

Results

180. rpm  20hz  11v ac
     
310. rpm  33hz  19v ac
     
890. rpm  96hz   54v ac
     
     

With the meter between 2 phases (starts) the above voltages doubled

My target cut in is for 48v battery charging so I think it will be about 200rpm

I am probably wrong but for what its worth here is how I arrived at 200rpm.

11v * 1.4 = 15.4v *3 = 46.2v / 180rpm = 0.2566v * 200rpm= 51.33v

As I said earlier maths is not my strong point but at least I tried!

I have no idea how to figure out how much power to expect but from reading old posts from Zubbley 140-150w per cubic inch of magnet 145*12=1740w

The resistance of a single phase of 6 coils is 0.3 ohms but I have read posts that say you can't measure the resistance with a normal meter? You need to know the total length off wire per coil to work it out, obviously I cant do that. If I apply ohms law to my know figures I get the following

V/R=I so 56v/0.3 *3= 62.22 amps

V *I = W so 56 * 62.22 = 3484 watts

But that cant be right surely so I will let those that know correct my mistakes on this!

I haven't got a clue how to work out the losses or the efficiency for this and

as for blade size I am guessing about 15-16 ft dia blades but I am probably wrong on that score as well!

  There is a little bit of cogging but its not to bad it would be similar to a future energy PMA and it has skewed lams? So I think it will be ok

I would like to be free from stall on this one as I will have a mechanical brake and a furling cable fitted for shut down.

 I have tried to include as much detail as possible but no doubt I have forgotten something vital so if I have just let me know.

 Any help, advise or comments would be most welcome

As Albert Einstein said "  If we knew what it was we were doing, it would not be called research, would it? "

Many thanks in advance

Russell