cheap source for large motors?

[tommydog]

I see many cheap secondhand motor options for small scale wind generation, such as treadmill motors, scooter motors, washing machine motors etc.  But what about if I want to build a turbine 10kw or more?  Are there any cheap motors that I can re-purpose?  Of course one can always buy expensive new motors to do the job, but cost is a big factor for me.  So looking for cheap secondhand devices where I can repurpose the motors.  Can anyone suggest anything?

[MagnetJuice]

Welcome to the forum tommydog.

Electrical motor repair shops are a good source.

Sometimes they have old motors that have been sitting around for years.

I bought a 7 HP from a local shop for $50. I also got a small 3-phase motor for free from the same shop.

Ed

[tommydog]

Electrical motor repair shops are a good source.

Sometimes they have old motors that have been sitting around for years.

I bought a 7 HP from a local shop for $50. I also got a small 3-phase motor for free from the same shop.

Ed

Unfortunately I don't have any such shops near to me.  Larger motors I have looked out are forklift motors, but they don't seem well suited to wind turbines.  Out of interest what were the motors out of that you got?

[MagnetJuice]

I have no idea what the motors came out of.

They were both 3-phase old 1700 RPM motors.

Ed

[bigrockcandymountain]

It depends what type of motor you are looking for.  I, and a few other people, have added permanent magnets to 3 phase induction motors. It takes a bit of machine work, and magnet gluing etc.  They make a great wind turbine. 

If you go this route, you are looking for a 3 phase 230v/460v  motor.  The speed rating should be close to 1750 rpm or 1150rpm assuming you are in north america.  575v or 600v motors aren't well suited.  3500rpm motors aren't well suited.

I prefer tefc which is totally enclosed fan cooled, but it isn't 100% necessary. 

They can be had for cheap off any buy and sell website, auction site, scrap metal place, etc. People buy old machine tools, and replace the 3 phase motor with single phase so they can run it at home.

  In Canada, kijiji is the place to look.  Probably craigslist in the states, unless there is something that has replaced it.

[SparWeb]

See if there are any motor rewinding shops near you.  They may have some in good condition that aren't worth the hassle to sell.

Here's my story:
https://www.fieldlines.com/index.php/topic,150227.0.html

[Adriaan Kragten]

The procedure how an asynchronous motor can be transformed into a PM-generator is described in my public report KD 341. Drawings of the armature for a 2.2 kW motor frame size 100 with an Indian stator stamping are given in public report KD 503. All public KD-reports can be copied for free from my website: www.kdwindturbines.nl.

[Bruce S]

There should be several write-ups located here from greats such as Zubbly, RuddyCrazy,etc.

Do a search in the upper right of the main (Landing ?) screen on either name and enjoy the read !! :-D.

Cheers
Bruce S

[Warpspeed]

Usually large and really cheap means a very old open frame motor like this:

The problem with that for a wind turbine is that its completely open to rain,wind and snow.

The more modern totally enclosed fan cooled motors (TEFC), the ones with the fins running along the outside, would be far more suitable, but unfortunately a more modern looking motor would be more sought after and therefore expensive.

[machinemaker]

First, what do you consider "large". I work in manufacturing and have seen a lot of motors go into the scrap bins. Usually, anything under 10 hp was considered not worth the labor and cost of rewinding.  I am of the belief that the two main causes of failure in an induction motor are: 1. windings failing (usually from heat) or bearing failure causing the windings to fail. In either case, you probably do not want to mess with the failed motor. Now if you can find old equipment that is being replaced you are in luck.
What I do see are DC permanent magnet motors being replaced with new equipment that runs AC motors with a VFD for speed control. Right now I have 4 new in the box 180VDC that I should just put out on ebay. Is there any use for these as wind or hydro applications?
Kent

[Warpspeed]

The original poster is asking about a suitable motor for a 10Kw wind turbine.

Motors of that size are going to be three phase and the windings arranged to run at 400 volts or more.  That is fine, run at about 1/10 the rpm it should produce about 1/10 the rated output voltage.  The difficulty, is that the safe current in the windings cannot be any higher than the original max running current on the rating plate.  So a 10Kw motor ends up only capable of 1Kw if run at one tenth the rpm and voltage.

So you might need a 100Kw motor for your 10Kw wind turbine, if you are planning for direct drive that is.
That might be at least half a ton of motor and not exactly cheap even at scrap value. 
A hydro system maybe, but raising a thing like that up in the air may be rather problematic.