How to choose the right generator motor?

[nathanca]

So I posted last week with a lot of questions about setting up my 200W Chispito-style wind turbine, and got a lot of good answers, thanks!! (If you want to check out the discussion, it's this one: http://www.fieldlines.com/story/2009/1/23/225639/562 )

I'm planning to connect my turbine to a 200W grid-tie inverter, but thanks to people's comments, realized that the inverter needs 14-28 volts, while my turbine is 12V. There are various fixes I could try, but I'm thinking it might be best to just buy the right generator motor, and replace the 12V one. So, any thoughts on the best one to get, and where to get it?

The current motor is 7" long, about 3.25" in diameter, the blades are 48" in diameter, and my area tends to have lower wind speeds, with occasional high-wind days. The current motor puts out DC, which is what the inverter inputs need.

So, any advice on which generator motor would be best here, and where to get it? Or any other ideas on how to get this up and running...?

[ghurd]

I do not see how 2V more will solve any of the issues.

If it is tied directly to the inverter, then the windmill only needs to spin about 5% faster. Maybe not even that much because it sounds like there will be no need for a blocking diode.

My concern (other than what was mentioned before) would be what happens in a 35MPH wind, when the windmill can make MORE than the 200W inverter is rated for.

Might consider some kind of circuit to dump some power at 25V, just to reduce the chances it will blow up the inverter.

Nobody is sure how those things are intended to operate.

Says solar on the front, but that logo sure looks like a wind turbine.

G-

[nathanca]

Thanks for the help here! Admittedly, directions for the inverter and turbine are somewhat limited, and I haven't found many people who are using that inverter yet. The inverter does say on the back that it's meant for wind and solar power, though the spec sheet doesn't mention wind. But I can still ask questions from the people who sold me both -I just need to know what to ask.

I talked to the person who sold me this wind turbine unit, and he said that the turbine should still feed the inverter when it goes over 17mph. I'm concerned that the wind in my area may a little less much of the time, but I'm willing to experiment and find out.

I would hope that the inverter knows when to dump extra power, and just sends it down the ground line... but I probably shouldn't assume this. Should I ask the seller this question?

And if I do include "some kind of circuit to dump some power at 25V" -How to I make or buy this? I know how to hook up a fuse, but not sure how to re-direct the power to be dumped.

[ghurd]

The inverter 'dumps' ALL the power, if I am not mistaken.

The problem is when the windmill can supply 250W at 29V.  Something is going to go.

The seller is most likely just a seller. He didn't design it.

He may know more about it.

Can't just send it down the ground line.

There are 'simple' Zener / power transistor circuits to bleed off some extra power.

Still a lot more complicated than a fuse.

G-

[nathanca]

Hmmmm, thanks that helps... just a couple more questions though:

If I install a fuse before the inverter, and it blows, then what? Will the turbine be damaged?

Also, the turbine seller/maker suggested hooking up the turbine to 2 car batteries wired in series, before the inverter. If I do this, will it potentially solve the problem, or at least provide some kind of buffer?

Thanks again!!

[ghurd]

If the fuse blows, the windmill will be running unloaded.  It can self distruct.

Fuse probably will not blow as fast as the inverter.

Not sure what to think about the 2 car batteries wired in series.  Lot of implications.

First is if the batteries are at 24V, then the windmill will have to hit 24V to do any good at all.

Next is the batteries will be drained by the inverter down to 7V each, and be ruined quick.  Like ruined this week kind of quick.

And they will have "More Than" 250W available.  So maybe the inverter has some kind of current limiting circuit.  That would mean it needs the over-voltage protection.

Without any decent documentation, it is all a guess.

Good luck,

G-

[nathanca]

Ok, I thought that battery idea had some issues, at least without some kind of charge controller.

I found some more specs about the inverter, and I'm going to make a new post to ask some other questions about it. It does say "Over-current protection: 20A", but I think you're saying I'll still have problems if the turbine exceeds a certain speed, correct?

I read that some wind turbines actually use a brake to keep things under a certain rpm, and I also read that there are some other ways to brake the generator... is there anything simple-ish that I can do to get this working safely?

[ghurd]

My '73 VW Super Beetle caught on fire because of the fog light fuse.

The fog lights were installed because the head light mounting areas rusted away.

A completely legal operation, even if my car was on fire.

"I thought that battery idea had some issues"

Yea!  Smoking Batteries!

"I read that some wind turbines actually use a brake"

Some do.

This home brew one did,

http://www.fieldlines.com/story/2008/11/8/63523/3798

This factory made one did too,

http://www.youtube.com/watch?v=dFU5XiMUrNw

Who cares about UL, CE, etc?

We could answer questions about the TS60.  It has papers for CE, UL1741, etc.

UL are the people who tell you if your house is in danger of burning down.

You are in uncharted territory with a device nobody knows who made it.

My 'Company' stuff is made to 9002 specs.

Xantrex is only 9001?  

That is frightening.

G-

[deloiter]

I have built several of the Chispito-style from the original plans using the original motor which is rarely seen anymore.  There are many similar but you really need the 260 volt version of this treadmill motor as the 130 volt version is useless IMHO.  I tried the 130 volt but I couldn't get enough rpms direct drive and I refuse to deal with gears or pulleys.  I have used the originally specified plastic cut blades (from several diameter pipes), carved wooden blades and the fiber Air-X knockoffs available on eBay.  I have never, ever seen anything near 200 watts.  That's not to say it won't do that in a gale so you do need to be prepared for any excess.  I have other gennies too so I have enough battery that they just laugh at what the Chispito can put out.  Therefore I don't have a dump on this unit.  

The most I saw from the unit was around 6 amps at a little over 14 volts.  I've heard that they will do more but that will be at a rather intense wind speed.  I know that's not what you want to hear but be prepared for less power that you probably expect.

[nathanca]

Thanks, good to hear from someone who has some experience with the Chispito-style turbine! And it sounds like the over-current problem is less likely than an under-current problem here.

Still, I'm wondering if an overload relay before the inverter might make sense? I could have the overload going to a water heater element, hopefully situated in my pool somehow. It looks like overload relays are fairly common, but nobody here has suggested one... am I on the right track?

[CmeBREW]

I second what deloiter said. I would say everything he said exactly. I used the 260v as he did, 12v cut-in almost 400rpm-- it was OK on windy days, but nothing great.

But my 4' diam wood blades were noisy and without furling, strong gails (+50mph) would break free of the magnet brake stop method (shorting the wires), and it sounded like a tornado siren combined with an ultra-light aeroplane trying to fly in a hurricane. Very scarey sound.  

I hope you didn't get stuck with that 130v (6000rpm/6Amp rated) or it is even worse. If I recall, 12v cut-in over 600rpm.  I would much rather have an Ametek from Windstuffnow.com and put my own blades on it and furl the thing to avoid making enemies of my neighbors.

[nathanca]

Ok, thanks for the help guys!! I'm finding out what the motor is, apparently the turbine maker/seller doesn't want to tell people because he's afraid they will copy his design and compete with him :p

Anyway, I plan to get the tower and turbine up and running this weekend, take some pics, and do some testing, then consider swapping out the motor.

I'll have to look into furling and/or braking, I'm not really clear how to do either on a unit like this. I'm making the tower somewhat easy to lower, so I might take it down during bad storms or something, but that has it's own problems too. Hmmmm....

[ghurd]

Furling makes the windmill "fold up" in high winds.

The blades are nearly sideways to the wind.  It can move up to verticle, but is usually sideways.

Braking shorts the output, hopefully causing enough load to mostly stop the windmill.

I do not believe it is idealy suited to most high-coil-resistance PM DC motors.  Many people use it as a form of control, in one fashion or another.

[nathanca]

Ok so the turbine maker says that it's a 260V Mcmillan treadmill motor; here's the specs:

2. -1/4 HP @ 260 VDC int.
   
1. -1/8 HP @ 130 VDC cont.
   
95. -260 VDC
    
5. Amps @ no load
   
0. -5100 RPM
   
   

Rotation reversible

Enclosure open

6" dia pulley/fan with 1-3/8" dia. 6 groove poly V pulley

Duty int. w/o cooling fan (not incl.)

Mount 2 threaded holes in side of body

Shaft 17 mm dia x 15/16" w/ 1/2"-13 x 7/8" long UNC LH threaded end

Size 7 3/4" x 4" x 4" excluding face plate

Shpg. 14 lbs.

I did some testing and took pics this weekend, but I'm going to put that in a new post here soon.

Thanks!!

[nathanca]

Hmmm, that first part didn't cut-and paste properly -trying again in plain text:

2-1/4 HP @ 260 VDC int.

1-1/8 HP @ 130 VDC cont.

95-260 VDC

5 Amps @ no load

0-5100 RPM