Author Topic: Playing with alternators.....PART 1  (Read 35714 times)

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Offline Bryan1

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Re: Playing with alternators.....PART 1
« Reply #15 on: May 04, 2012, 10:57:34 pm »
G'day Oz,
                Well mate with that Murphy character well laid plans always goes wrong......

I set out this morning thinking that ol' B&S water pump that the boss put diesel in would make a good donor but I needed to get my sack truck going. Stripped out the old tubes and put in 2 new ones then off to find the 12 volt air compressor. After my son's 18th last night I dragged him out of bed at 11am to ask him where that compressor was...... The response last time we used it the compressor was put in a secure place and I forgot where it is......

Went up to my shed to find the batteries on 24.3 volts after a week of charging so turned the inverter off.......

Started stripping that alt to take a few pic's and the camera batteries went flat.......

Well 3 strikes from Murphy and with more Boag's in the fridge and the boss on the prowl went down and got more cider only to find the bottlo was closed for the weekend.

Anyway with the boss going out tomorrow and fresh batteries for the camera once this body is 0.00 on the alchy tester the sack truck tyres will be fixed and this journey into a 24 volt alt conversion the Oztules way will get under way.

Cheers Bryan

P.S. on another note it was said the Mr. Oz.Tules had more of the red/white nectar to last until next year so an offer to be had. 5kg's of 1.6mm 14awg magnet wire for a doz of the FI golden stuff........

Offline ksouers

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Re: Playing with alternators.....PART 1
« Reply #16 on: May 05, 2012, 01:41:18 pm »
It's friday.... so we have  imbibed too much of the golden stuff to comment further at this stage, and the boss is in party mode, so I'm signing off for now.

Yes, it's surprising how easily they come apart if you slip them into thick walled tube........
 and use a dinky little press like this.

Nothing like a little hydraulic help. Both kinds!


Kevin
As far from the city as I can get but still keep my job.

Offline oztules

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Re: Playing with alternators.....PART 1
« Reply #17 on: May 05, 2012, 11:50:57 pm »
Bryan...... I have important news for you....

You can never have too much on hand..... just in case of alien invasion or something.

You cant drink enamel wire when you decide it's time to go silly.

But more importantly.......

The postage from that miserable postal service we help fund is extreme from here.

Sent 6 bottles to the Barossa  SA, and it cost near $40.00.... just to send..... $80.00 /dozen is insane for postage..... particularly when to buy it into here it costs only $10.00/case.

So I'll be forced..... forced mind you, to drink it here rather than send it elsewhere.... :P :P :P

I too have just pulled apart an alternator and mangled it to how I wanted.... and will show pics.


...................oztules
Flinders Island...... Australia

Offline ChrisOlson

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Re: Playing with alternators.....PART 1
« Reply #18 on: May 06, 2012, 08:20:08 pm »
In the above stator, there are three"skein" windings, wound in such a way as to provide effectively three sets of 12 legs.... equating to 6 full coils per phase... or 12 half coils? if there is such a thing.

oz, in the serpentine winding configuration, that's considered 12 coils.  At least in my experience, you get the same voltage from it that you get if you would wind 12 full coils and reverse the polarity of every other one in each phase.  Except that with the serpentine winding you eliminate one winding head on each coil.

I think we had a discussion about this someplace else awhile back, and I pointed out that this has been used in automotive alternators and industrial motors for years with great success.

Edit:
At least in my experience, you get the same voltage from it that you get if you would wind 12 full coils and reverse the polarity of every other one in each phase

I referred to my notes from a few years back on the serpentine wound axial generators that I built and the above is wrong.  The ones I built were 12 pole.  I got the same voltage you would get from 6 full coils per phase with the same number of legs in the serpentine phase coil as poles.  The phase resistance was 8% less than winding 12 full coils at half the turns, and wiring them series.  However, they had terrible problems with harmonic vibration in the phases.
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Chris

Offline oztules

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Re: Playing with alternators.....PART 1
« Reply #19 on: May 07, 2012, 03:01:44 am »
It's good we can agree on this aspect.

It all comes down to number of legs in the system. 12 full coils will have twice the EMF per rev as a 6 full or 12leg  serpentine winding will have. How we arrange the coil ends is of no consequence to the EMF generated... simply put 12 coils will have 24 legs to cut, and 6 coils only 12.... twice as many same turn coils.... twice the EMF.

Stacking factor and physical constraints and resistance are a different matter. I suspect if you try hard enough, the outcome should be very similar, and stacking technique will be the difference in the resistance. The coils ends will be the same for the same turn number, only the coil interconnects of the full coil design should be the difference. I understand your experience was slightly (8%) different, but if there was to be always an 8% advantage to serpentine winding, then there would be no full coil devices built.

I can promise you that when I rewound the 90 coil AWP stator, if I could have gotten away with half the turns or half the coils for the same kind of result I would have taken it.... sadly this is not so, and magic is only possible when trying to envisage  primal forces and planck time scales. (whats gravity I ask.....)

My first guess at why car alternators always have skein windings and almost nothing else does, has more to do with the almost unlimited rpm available, and cooling and space.

As I mentioned earlier, armature reactance is the major factor in auto alt output, and can be mitigated by less turns at more amps (ampere turns.... which would need more revs to compensate, but thats of almost no consequence for car and truck alts. One minute they are running a few thousand at idle, and next can be 18000 at high revs. Volts per turn are not critical. They just need to design for cut in around idle X step up ratio. They also need to design in enough reactance so that things don't go pear shaped when the revs come on,and then we need to  self limit. This allows for simple regulators, and no shredded belts...... Imagine if you developed a few hp at idle, what would you develop at full revs if the regulator was turned on full, and the battery and load could take it... even for very short bursts if it didn't self current limit with reactance...... scary.

So thick wire, open coil structure, no care of rpm, ease of manufacture, easy cooling, and current limiting...... skein winding is a good option.

If it offered any noticeable improvement over normal full coil winding, the alternator at the power station would use it.

8%  for 24/7 is a massive diesel saving..... but it's just not there.... and I know as I have one here.

1098-0

Even the exciter stator is wound normally...... there is a reason for normal apparently..

1099-1

You know it's big when I need to use my  trac 955 to unload it.


......................oztules




Flinders Island...... Australia

Offline ChrisOlson

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Re: Playing with alternators.....PART 1
« Reply #20 on: May 07, 2012, 08:59:20 am »
oz, I've never been able to improve on Hugh's basic 4:3 pole/coil ratio flat three phase design as far as internal resistance in an air core axial.  I've tried and failed with 1:3 units.  Technically the serpentine winding is a 2:1 ratio unit and it was the first time I had been able to get lower resistance for a given voltage in a given size.  I think that's because it was ridiculously easy to wind.  I wound them on a board with pegs in it, hot glued the windings so they wouldn't come apart and stack three of them in the mold.

I think I got the lower resistance because it was wound tight and didn't waste any copper with loose coils.

But it had a HORRIBLE vibration problem.  I attribute that to the fact that you're exciting three big loops of wire 120 degrees from one another.  As you excite each phase it vibrates against the phases it's in contact with from being overlapped.

Hugh's design is beauty in motion because the stator is excited in thirds, equally distributed around the winding, and you don't have physical contact between the phase coils.  So it has less vibration.

I think the serpentine winding is better suited to radials where the vibration of the wires is dampened by the core.  It was a dismal failure in my axial experiments because the windings wouldn't last with the terrible vibration and noise they made.
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Chris

Offline niall

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Re: Playing with alternators.....PART 1
« Reply #21 on: May 07, 2012, 03:27:31 pm »
mmm...

never thought of the hydraulic press... ???

the man who donated the box full of old alts had something very similar i think at the back of his garage ....

 

Offline uber39

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Re: Playing with alternators.....PART 1
« Reply #22 on: July 06, 2014, 07:44:45 am »
Hi all, sorry if you've seen this before
http://www.microcogen.info/index.php?topic=157.0
but not a bad way to charge different volt batt banks

Ian