Author Topic: But can it be converted to a PMA?  (Read 4927 times)

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wael

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But can it be converted to a PMA?
« on: July 04, 2015, 06:20:00 AM »
Hello everyone, found this forum a while ago, read a couple of posts, got interested and started to build a small PMA project.
I only need a few expert tips, help and tricks to get the first step =)

Im trying to build a PMA that would charge a battery through a controller. Then run it to an inverter to get 220v the power will be used for small appliances (not over 200W for now).

Found a very old motor made in Yugoslavia, from what I could see and read:
* single phase asynchronous motor
* 220v 50 Hz
* 0.25 HP
* comes with two capacitors

ive read somewhere that there is a difference between motors with caps for starting/exciting the motor and different copper wire thickness (I think I its less usable if its the later?).
So anyway, I've put pictures of the motor so you guys can check it out.

the rotor is quiet heavy and I was wondering if I could machine a rotor out of wood or plastic where I could fit the magnets. thought it would be lighter when there's low wind? :)

Thnx


SparWeb

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Re: But can it be converted to a PMA?
« Reply #1 on: July 04, 2015, 10:39:28 PM »
Hi
Welcome to Fieldlines :)

I'm sure you can get something out of it, but it won't be a lot.
The case is open, which means that lots of water/dust/snow will get inside and rust it out.
The shaft is fairly thin - for a wind turbine to last you need big shafts and bearings.
Are you interested in re-winding the wire? 
The electrical configuration now is another strike against it- single phase doesn't run smoothly as a 3-phase machine can, and it probably won't allow a lot of current to flow.  Being a capacitor start + run motor that's a sure sign, in fact.  Lastly, as a low-power motor, it will be a fairly low-power wind turbine.  To make a rough estimate:

As a motor:
0.25 HP = 750/4 = 188 Watt
188 Watt / 220 V = 0.85 Ampere

As a generator, if you use a 12-volt battery:

14 Volt * 0.85 Ampere = 12 Watt

If you live in a windy place, this can maintain a bank of batteries with about 20 Amp-hours capacity.  More if you don't demand much from the batteries, less if you use the battery power often.
There are rewards for having a higher-voltage system, and it will also benefit you to run the generator at higher voltage too.  If it can - your motor may not offer wiring options to do this, without re-winding the wire.
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tanner0441

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Re: But can it be converted to a PMA?
« Reply #2 on: July 05, 2015, 08:02:44 AM »
Hi

You also said machine a new rotor out of wood, this will reduce the output even more because there is no return path for the flux.

Brian.

wael

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Re: But can it be converted to a PMA?
« Reply #3 on: July 05, 2015, 07:14:45 PM »
Hi

First of all thank you guys for your fast replies!

Sparweb:
 I had in mind to close the case, keep it clear from dust/snow/rain.
I wanted to build a small generator to charge a 12v batt, which I would use it as a reference in my workplace and to power my uncles small cabin (couple of bulbs maybe a tv or a radio), also the boss man likes inventions created by yourself that are useful to others, part of the company's name is "ECOENERGY" so looking for a small raise not much =). Btw im a mechanical engineer msc. HVAC, totally different line of work here =) but hey ECOENERGY that's the stuff =D.

Back to the genny...

A small project, involving:
* charging a 12v batt

* using an inverter (300W, 12v/220v) for small appliances (light,tv,radio nothing more)

* if needed (think I will) power cut off, rectifiers (definitely needing that) solar panel controller (think that's the power cut off?) etc...

* would love to not mess with the rewiring never done it but I wouldn't run away if I knew i would get a decent amount of V's at low rpm (with steady frequent charging) from it and get a step by step guide for how to re-wind it.

* thought of build a VAWT cause i have 85 - 90% of material and a not too high place to put it with a lot of free space (no obstacles - sometimes very strong gusts of wind but frequent low to medium wind almost all year)

* HAWT i could use them also but i think ill have a lot more work with them and materials

Btw if I would do the re-winding could I use the same wire from the stator or get a new one?

Brian:
i read something like that somewhere last night so i guess ill leave it like that then, thanks.


joestue

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Re: But can it be converted to a PMA?
« Reply #4 on: July 05, 2015, 07:47:49 PM »
That motor you have with its two identical capacitors is designed to be reversible and provide a good amount of torque in both directions.
You should find that both coils are 90 degrees out of phase (2 phase motor) and equal in number of turns and wire gauge.

so you can get good power out of it, if you can find the right size magnets, but you'll need a belt drive or something to increase the speed.

usually they are wired like this:
http://2.bp.blogspot.com/-qFTb62zsD9A/UvSdl-kSBWI/AAAAAAAAAtk/LFt3TDIDfTc/s1600/Capacitor+Motors+6D+copy.jpg


i am really supprised such a high slot number was chosen.
54 slots isn't really a good number. you could rewind it for 6 poles or 18 poles if you really want to...
My wife says I'm not just a different colored rubik's cube, i am a rubik's knot in a cage.

wael

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Re: But can it be converted to a PMA?
« Reply #5 on: July 06, 2015, 03:10:00 AM »
Thanks Joe for the info, didn't really thought about that or read about it yet.
I've noticed the coils but wasn't quiet sure about the phases.

i did read on how to position and where the magnetic pole pieces should sit (i think it was zubbly's guide), i was thinking of round permanent magnets but still too early for that until i figure out what to do with the stator wiring.

If u get a chance can you explain about the 54 slots why isn't it a good number.

Much appreciated =)

tanner0441

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Re: But can it be converted to a PMA?
« Reply #6 on: July 06, 2015, 05:47:39 AM »
Hi

If you want part of the load to be lighting then I would go for 12V LED. I have a camper and I stripped all the 12V flourescent lighting and fitted LED strip lights. I also have a roll of LEDs and you cut them into multiples of 3 and feed them with 12V.

If you use an inverter for lighting there is the inefficiency of the inverter to get the voltage up and then the added inefficiency to bring it back down again to the voltage the lamps need.  Also again if you want to run a TV or laptop a lot of the modern TVs have a power supply that brings the mains power down to 12V and even though the power supplies for laptops are around 18V I have yet to find a laptop that won't run on 12V.

Brian

Flux

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Re: But can it be converted to a PMA?
« Reply #7 on: July 06, 2015, 07:30:27 AM »
I agree with the others, you can get something out of it and as an experiment to gain experience it may be fun. In reality it is unsuitable in many ways and would probably need to work on a 48v system to use the original winding.

The poor construction and lack of bearings mainly confines it to experimenting. Using wood for magnet rotors and considering using it for a vawt will mean you accepting a tiny output and it will need a good wind site to do anything at all.

If it is to gain experience, try it. Otherwise buy a 10W solar panel and get more output.  Practical motor conversions for useful power need motors of 1hp and upwards to justify the effort.

Flux

joestue

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Re: But can it be converted to a PMA?
« Reply #8 on: July 07, 2015, 12:33:59 AM »
If u get a chance can you explain about the 54 slots why isn't it a good number.
look here:
https://www.emetor.com/edit/windings/
Because 8,10,12,14,16 poles require really complicated winding schemes.
My wife says I'm not just a different colored rubik's cube, i am a rubik's knot in a cage.

wael

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Re: But can it be converted to a PMA?
« Reply #9 on: July 07, 2015, 03:24:38 AM »
Well i guess ill do a little experimenting then with this motor. Doesn't hurt to try a few things before stepping into deeper waters =)

Anyways if i could make it to produce 15v max i would be happy.
Ill slap on some magnets read the output see whats going on in there.

ill post the results as soon as i can.

thank you all for your help tips =)


 

Flux

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Re: But can it be converted to a PMA?
« Reply #10 on: July 07, 2015, 03:40:42 AM »
Give it a try, you will learn a lot that way. I didn't want you to put a lot of effort into it and be disappointed.

If you can get some reasonable magnets in there on some form of iron core you will not struggle with volts.You will struggle with current on a 12v system but 60W may not be out of reach.

You need to establish the number of poles in the winding and use the same number for the rotor. I can't read the data plate but if it is rated for a speed just under 3000rpm it will be 2 pole. If about 1500rpm then 4 pole. From the picture of the winding I suspect 2 pole. A 2 pole magnet rotor will need to be made up of several small magnets to deal with the curvature.

If you can find information on Zubblys rotor construction with round magnets that will give you a good starting point.

Flux