Good test run this weekend

[kc5etv]

My 10 ft Turbine did well this weekend we had winds 20 to 35 mph, did get some data will try to get it all together and let you know how it did.

Thanks for all your help..

Here it is on Youtube if you want to check it out.

http://www.youtube.com/watch?v=HFRm8TyvH8E

[tecker]

Cool .You can tell it was under load and it looks like those blades are performing well  . Maybe a plywood tail at a later date .

[kc5etv]

The tail is what I do need to work on, it was smaller and then I added to it and now I think it may be to heavy, I did notice this weekend it was trying to furl a bit in the high wins 35 to 40 and the rpm was around 350 to 400 rpm is that letting it run to fast my amp meter only goes up to 10 amp's and it was well above that, at about 250 rpm it is over 10 amps so not sure what it was doing at 350 to 400 rpm.

Thanks for your comment

[TheCasualTraveler]

Wow, that was pretty! Very, very nice. Congrats.

[Flux]

I don't have enough details to form much of an opinion on this but somewhere along the line your efficiency seems quite low. You say 10ft and somewhere I seem to remember something about 12v.

If you see 10A at 250 rpm and you are going up to 400rpm then you will probably be in the 20A region. For a 10ft machine to be producing about 20A in a 40 mph wind you have missed the target rather badly somewhere but I don't have enough details to know where.

If it is an alternator based on Dan's 10ft machine then I would not expect it to get up to the 400rpm region and if it did it ought to be up near 100A at 12v

For a normally operating machine to not be furling at 40 mph is asking for trouble but if you are not extracting more than 250W it may be perfectly safe.

Are these real wind figures or figures from weather reports or some local airport?

Flux

[tecker]

A meter shunt is fairly easy with another meter to calibratte with . Just probe downline with a sharp point probe for 1 amp  as the amperage is holding steady at 10 amps and land the neg side of your panel meter there .

[tecker]

one t in calibrate

[kc5etv]

The wind speed is from the airport and weather report. I hope to get wind speed setup at home soon. As far as furling at 40 mph the tail is trying, this weekend I will remove some of the tail and see if I can get it to start sooner. It is set up like Dans 12 volt 9 coils 24 magnets #14 wire two in hand 36 turns and it does start charging at about 135 rpm and at 350 rpm is at 10+ amps and get there fast. I will be getting another amp meter soon ( What is a Good Range for the amp meter?) The tach I am using is a program I found ( Serial Tach via the internet ) and took at door alarm switch and mounted it on the turbine, not sure how close the rpm is.

What is a good target number for this machine at 350 to 370 rpm ?

Thanks for your help.

[Flux]

Thanks you have given lots of useful information here.

If it is a copy of Dan's 10ft then cut in at 135rpm seems normal enough. Now at 350rpm you have an emf of 350/135 x 12 = 31v. Now that is 19v above battery volts. For a current of 10A that implies a total circuit resistance of 1.9 ohms which is crazy for a 10ft 12v machine. Have you connected the thing with string or something, the thing needs to be got down to a fraction of an ohm to do any good. No wonder it is going up to 400 rpm there is no load on it. The furling as intended by Dan isn't going to work as the prop is racing away and will be seeking the wind and this changes everything.

I don't have figures for that alternator but running something similar from somewhere else I think you will have a winding resistance of about 0.2 ohms, about the most you can stand in the line connection is about the same again and ideally you ought to be keeping it down to .1 ohm.

What is that ammeter thing you are using, I am wondering how much resistance is in there, you ought to be looking at something to measure 60 amps and that should be using a shunt for such a current.If it is some moving iron current indicator from a cheap battery charger or something then it may have a lot of resistance.

Flux

[kc5etv]

Need to use spell check

[kc5etv]

I think you hit on the head the amp meter is a GE 0 to 10 amp meter. I have no shunt so I took it out of line and hope to see better Performance. I will be looking to replace it with the right meter, do you have any suggestion ?

Thanks for your help.

[Flux]

Now that you say it is a GE meter I am not so sure it is your trouble. There could be a large number of different types of meter but if it is intended as a dc meter then something from a respected maker like GE would not have enough resistance to cause your problem. Typical volt drop for dc moving coil meters at fsd is 75mv and that would only equate to 7.5mohms. If it was 10A moving iron from GE then it still wouldn't be serious.

At least if you remove the ammeter you can see if the on load rpm drops way down on what you are getting with it in.

Good ammeters and shunts don't come cheap. If you know something about meters you can save a lot of money by spotting 75mv moving coil movements ( this information is usually given somewhere on the scale or on the label. The actual scale figures don't matter much but it is more convenient if the scale has something sensible that relates to your expected current ( eg if it was scaled to 600A then you could ignore the last zero). Precision shunts cost as much as decent meters but for the accuracy you need you can measure the volt drop across a length of wire.Someone here has given lengths of copper wire for use as shunts but I wouldn't be able to find it.

Until you find out what is the matter with your mill you have no real idea what size ammeter to go for so I wouldn't invest big money until you have sorted that out. I would expect a 10ft mill to peak over 600W so I would guess 60A would be adequate but if you got a few good gusts that caught the furling out you may see over that.

To give you some sort of guide with sensible line resistance you ought to hit 50A below 400rpm.

Flux

[TomW]

Flux;

I used lots of copper wire shunts over the years.

Essentially a 1 foot long piece of #10 solid copper wire will drop 1 mv [millivolt] per amp of current thru it.

Cheap, simple, accurate enough for RE and can handle something like 35 to 50 amps easy.

I did a couple posts on it back when I was doing more hands on.

Wearing out sucks, my friend.

Tom

[Flux]

Thanks Tom, that is the figure I was thinking of. I can't remember it because we are metric and #10 wire here is not available.

Flux

[kc5etv]

Thanks for you help, I will try the # 10 wire at 1 foot and use my meter it has (mv) on it ans see how at does.

[kc5etv]

Thanks for you help, I will try the # 10 wire at 1 foot and use my meter it has (mv) on it and see how that does.

[TomW]

Les;

I would suggest you use a longer section of wire than the 1 foot. Attach it in the line at its ends and attach [I like split bolts] one "sense" wire near the main connection on one end. Do not use the same point as the power connection. Then measure off 1 foot from the first sense wire, strip off an inch or so of insulation and clamp the other sense wire to it there. Split bolts allow you to calibrate the shunt wire length by sliding it to a different position on the shunt wire [the #10] if you can beg, borrow or steal an ammeter to set it up with. Once the proper points are found you can solder on the sense wires for permanent use.

Thats the nutshell version. I actually did a fairly detailed writeup on it once but couldn't find it. You can use other gage wire as a shunt but #10 just happens to be perfect at 1 mv per amp across 1 foot.

Good luck with it.

Tom

[Ungrounded Lightning Rod]

Ditto but I'd just solder the two sense wires on.  Then sweat the joint and move them back-and-forth to get the calibration I want.

The resistance of the thin layer of solder is so much higher than that of the thicker copper wire that it's not an issue.  (And if it were it still gets tuned out by the 'heat it and slide it until your meter agrees with the reference meter" calibration.  B-)  )

Advantage of solder over clamps is avoidance of corrosion, vibration, and other screwups once you've gotten it calibrated.  Just cover the joint with a bit of "liquid electrical tape" for insulation and you're done.

[kc5etv]

Hey All

I am working on the shunt and hope to have it working soon and thanks for the input, the winds are none so we are still waiting to see how it does, I will let you know. Thanks again from West Texas.

[kc5etv]

Ok I have a 0 to 600 mv meter can I use it as a 60 amp meter and if so can I still use #10 wire and if so how long ? I do have some # 6 AWG also if this is better.

I have tried to use this web site but it is not working for me, I just install 3.7 ft of # 6 and the meter acts as a 6 amp meter, Aim confused.

Any suggestion.

Thanks

[kc5etv]

This is the web site : http://www.uoguelph.ca/~antoon/gadgets/shunts/shunts.html

[ghurd]

Except for the data problems,

It looked Great to me!

G-

[TomW]

Les;

As a generalization, any cable will work as long as it can handle the current flow and you can find a point where you get the proper scaling. The #6 will drop less voltage per amp per foot than the #10.

There are lots of ways to get there. Just beware of not overloading the "shunt" wire that carries the current. I have matched a good few odd duck meters for my needs but have learned to look for more common full scale Mv ranges.

I have often used longer pieces of #10 to get a match for higher voltage meters. So to get the 600 Mv movement to read 60 amps full scale would need about 10 times the length of #6 as it has to read 6 ams FS. Beware, I make math errors often. But you pretty much can match any meter to a wire shunt of some type. There are some really odd meters out there salvage / Ebay. Most give either full scale [FS] Mv, current in microamps [Ua]  or resistance in ohms [that omega symbol] either on the scale card of the face or a label on the case. From there you can usually use ohms law to get a match sorted out. Some meters are just way too sensitive to be easily matched.

Good luck with it.

Tom

[kc5etv]

I want to thank you for your help, I have finished building up the shunt, and here is how it came out. Here is the web sites that also helped.

http://www.uoguelph.ca/~antoon/gadgets/shunts/shunts.html

http://amasci.com/tesla/wire1.html

1. Got a 0 to 1 mv meter # 60-158
   
2. The internal resistance at 1 mv is 120 ohms
   
3. To Calculate with # 10 wire, circ of wire is 10383 and ohms/ kft .9989
   
4. To Calculate meter to 0 to 50 amps . 50amps/.001amp = 50000
   
5. 120ohms/50000= .0024/.9989/1000=2.402 ft of  # 10 wire
   
   

I compared it with a amp meter I had and it looks to be right on.

Thanks again

[kc5etv]

I want to thank you for your help, I have finished building up the shunt, and here is how it came out. Here is the web sites that also helped.

http://www.uoguelph.ca/~antoon/gadgets/shunts/shunts.html

http://amasci.com/tesla/wire1.html

1. Got a 0 to 1 mv meter # 60-158
   
2. The internal resistance at 1 mv is 120 ohms
   
3. To Calculate with # 10 wire, circ of wire is 10383 and ohms/ kft .9989
   
4. To Calculate meter to 0 to 50 amps . 50amps/.001amp = 50000
   
5. 120ohms/50000= .0024/.9989/1000=2.402 ft of  # 10 wire
   
   

I compared it with a amp meter I had and it looks to be right on.

Thanks again

[kc5etv]

I want to thank you for your help, I have finished building up the shunt, and here is how it came out. Here is the web sites that also helped.

http://www.uoguelph.ca/~antoon/gadgets/shunts/shunts.html

http://amasci.com/tesla/wire1.html

1. Got a 0 to 1 mv meter # 60-158
   
2. The internal resistance at 1 mv is 120 ohms
   
3. To Calculate with # 10 wire, circ of wire is 10383 and ohms/ kft .9989
   
4. To Calculate meter to 0 to 50 amps . 50amps/.001amp = 50000
   
5. 120ohms/50000= .0024/.9989/1000=2.402 ft of  # 10 wire
   
   

I compared it with a amp meter I had and it looks to be right on.

Thanks again