10 ft machine performance expectations?

[halfcrazy]

ok i have had my 10 ft machine up for about 4 months and have a few questions.

first off it is built to Dans plans and the stator was wound by Dan. the blades are from Scott and Dan. the machine is hooked to a 48 volt battery bank. The machine is on about a 65ft tilt up tower and pictures can be seen at my website www.solar4maine.com

My question is i seem to reach cut in speed very easy hardly a breeze and we are making 50 watts. but in stronger wnds it seems like it has a hard time producing? i mean i have seen 16-17 amps in strong gusts and on one ocasion was able to see it produce 21 amps. but it seems like it takes a lot of wind to get there.

the turbine has 10 gauge wire up the tower 70ish feet and 250 ft of 10 gauge wire running into the house. would this have any adverse effects on anything?

I am going to try to get some wind logging equipment up on the tower to be able to give data by wind mph. but does this seem about right or should i be looking at opening the air gap up or something?

[halfcrazy]

oh yeah the machine is wired identical to dans machines and the rectifiers are in the house 320ft from the turbine

[Nothing40]

10 gauge wire seems kind of small (in my opinion) for such a long (300+ft) run.

I'm no expert,just my gut feeling.

[wdyasq]

Is that a 320 foot run - or, is the run 320 foot and there is 740 foot + of wire .... It makes a difference. The difference is sizable.

Ron

[TomW]

My 24 volt system with 2 turbines 300 feet from the batteries and 50 amps max ever recorded is using 1/0 [single aught] aluminum cable from the tower carrying DC and I think its on the small side. I use #10 down the towers, however which are 30 and 60 feet tall.

I used to have #6 to the batteries and it was very lossy with a fair bit of power heating cable.

Bigger is better for feed lines, IMHO.

Tom

[scottsAI]

halfcrazy,

A breeze and better is required to hit 50w.

Below chart is conservative (theory) performance of a 10 ft wind turbine

MPH 07 = 49.33 w

MPH 08 = 73.63 w

MPH 09 = 104.84 w

MPH 10 = 143.81 w

MPH 11 = 191.42 w

MPH 12 = 248.51 w

MPH 13 = 315.96 w

MPH 14 = 394.62 w

MPH 15 = 485.37 w

MPH 16 = 589.06 w

MPH 17 = 706.55 w

MPH 18 = 838.72 w

MPH 19 = 986.42 w

MPH 20 = 1150.51 w

MPH 21 = 1331.85 w

MPH 22 = 1531.32 w

MPH 23 = 1749.78 w

Notice 18MPH to hit the 838, very good wind. Due to wiring losses you need a 20 MPH wind.

Power lost with 10 awg wire is high with high winds.

http://www.powerstream.com/Wire_Size.htm

Tower 70 ft with 250 ft more to house is 320 ft, 10 awg copper wire at 20amps will drop 13.45v or 27% loss. I would consider this excessive. Except many are finding adding resistance can be beneficial.

Your currents are lower than others due to 48v system.

Might not be what you're expecting, looks OK to me.

Have fun,

Scott.

[Airstream]

You have three 10awg copper conductor delivering 3-phase 320-feet away from turbine?

The Dans' current 10' Kit Machine is conservatively rated at 800-900w in 20~25mph winds... The 17 amps you've seen (at true 48V string battery charging voltage plus diode losses is about 60V) at 60V x 17A is 1020 watts ON TOP OF line losses!

I got not very far at calculating true line losses for 60VAC 3Ø over 10AWG - for 18A I came up with ~9% losses. (one example used http://www.scoraigwind.com/CABLE/index.htm)

Using handy online calculator to go with 1 one-phase 48V (two wires) over 10awg @ 320' is 23.28% voltage drop!

I'm also wondering who gave Flux the night off : )

[Flux]

20A or 1kW is not bad for that type of 10ft machine and is realistically all you can expect the thing to stand.

The only real issue is the wind speed at which you get it. As you have no idea of wind speed then there is no way of knowing.

 "i mean i have seen 16-17 amps in strong gusts and on one ocasion was able to see it produce 21 amps. but it seems like it takes a lot of wind to get there."

That may imply that you are in a poor wind area ( as most of us are). There sometimes isn't much energy in gusts. If you get sustained good wind it may perform a lot better.

Unless you can devise a way of measuring prop speed it is hard to know where you are working.

It sounds as though the cut in is plenty low enough and with little line resistance I would expect you to stall and it does sound a bit that way now but you should have enough line resistance to avoid it I would have thought.

See if you can measure prop speed from the frequency of the incoming ac, that will give a better idea of where you are working.

You may get some idea looking at it, if it is slow and lazy and very quiet then you could try adding an ohm or two in the dc positive line and see if it livens up.

If it is already fast and noisy then you may have more line loss than desirable .

My 10ft machine does 50A quite easily into a 28v battery ( not a typo) in winds around 25 mph. That would be something like 25A for your 48v.

You won't get that sort of performance as my alternator is far better matched in the 25mph wind region and uses a boost converter to deal with the low winds.

I am inclined to think that you are not far off target but without reliable wind data it is nothing but a guess. If you average 200W on most days with a 10ft machine you are doing ok.

Flux

[scoraigwind]

The #10 wire size is a bit small by conventional measures and you will get over 20% loss at 20 amps or so, but I suspect that it would be unwise to use a bigger wire.  If the battery voltage is low then the turbine will probably stall using thicker wire, and you will not see very good performance.  

If you are wondering if the turbine is stalling and you cannot measure the windspeed to check up on this, then try adding resistance to the line to see if that improves the output.  I find that sometimes, if the battery voltage is low, you can get a big increase in output by adding resistance to the line and upping the voltage at the turbine.  The nice thing is that it's quite easy to try and it will either work or not work so hat you see is what you get.

Try adding 1/2 ohm of resistance if the battery voltage is low (around 48 volts).  At 6 amps output this will pull the voltage up to 51 volts, and the speed up correspondingly, and may get the turbine out of stall.  Or may just waste power if the turbine is not stalling.  Easy to find out.  Trial and error.

have fun

[halfcrazy]

thanks for all the info guys. it does seem that it may be performing as expected. right now the trees are bairely wiggling and it is making a steady 4 amps or 200ish watts.

and a little more data my rectifiers are in the house so we have 3 10 gauge wires going from mill to rectifiers and that distance is 320 ft so i have 960 ft of #10 witch i know is marginal but it was what we had and wanted to try it.

I will work on getting an anemmometer ?sp on the tower when i let her down for service in a couple weeks

[scoraigwind]

Just a quick note to say this.  If it is prone to stalling then it can also work very well in low winds up to about 200 watts.  It's when the wind picks up a little more that it could stall, and that is where the output just stays at 200 watts instead of being 600.  That's the usual scenario with stalling.  The turbine charges very nicely in a very low wind, and then fails to get going in stronger winds.  Often stall does not happen except with low batteries.  Low batteries can tip the balance.  It's an unstable thing.  The more it stalls the lower they tend to get.  Unless you have a big PV.

[halfcrazy]

ok i am pretty shore it isnt stalling as it does seem to evenly ramp up in output evenly i really think it is working as designed

now for a headscratcher if one was going to feed the turbine into a mppt controller wouldnt that allow us to rewind the stator for a higher voltage and have the controller keep the trubine in its "sweet spot" and if so what voltage would you recommend winding for to charge a 48 volt battery?

[Flux]

"now for a headscratcher if one was going to feed the turbine into a mppt controller wouldnt that allow us to rewind the stator for a higher voltage and have the controller keep the trubine in its "sweet spot" and if so what voltage would you recommend winding for to charge a 48 volt battery?"

When you have found your mppt controller that will decide the voltage.

For grid tie these mppt inverters do use high voltage but there is no need to do so for battery charging. If it was a 12v system then a higher voltage would help to reduce line losses but for 48v that is no big issue and starting at 48v at cut in seems the most logical. If you track up to 3 times cut in wind speed then the converter input will be up to 150v. If you track up to 4 times cut in speed the volts will be up to 200 and that is bad enough to deal with from the converter point of view.

You will almost certainly need to clamp the top end voltage unless your furling is extremely good and even if you manage that, it will be instant smoke from the converter if you loose load without a voltage clamp.

As far as the turbine is concerned voltage doesn't matter one bit but the controller will be worried and will decide your choice.

Flux

[halfcrazy]

ok i will be able to clamp the uper voltages and should be able to handle 200-250 volts into the mppt controller. we will see when we get the equipment set up and then maybe we will have to think about the stator or maybe not?