Anotherpower.com Forum
Project Journals => User Journals => Chris Olson => Topic started by: ChrisOlson on February 12, 2012, 05:52:56 pm
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This is the stator for a new turbine I'm going to experiment with - just got the stator done today:
[attachimg=1]
This new turbine is a 3.2 meter machine like the last one, with a geared generator. But I'm using a 12 pole 9 coil three phase neo generator on it. It will hit 180 open volts @ 450 rpm (blade speed), and it's design max power @ 400 rpm is 160 open/147 loaded @ .47 ohm internal resistance for 27 amps, or 3.9 kW power output @ 91.9% power efficiency at the generator.
It will require a lower gear ratio than my previous ferrite generator, which will improve the drivetrain efficiency by about .6%.
The purpose of this experiment is to see if I can build a CHP turbine. Run the Classic 150 controller right up against its voltage limit with the blades running at TSR 6.5 so the voltage clipper will be required to come on just to regulate the voltage during normal operation. Then dump the excess to three phase water heating with the clipper as part of normal operating parameters.
The reason I chose a neo gen for this one is because it's hard to get that sort of efficiency and voltage from a ferrite generator for a turbine this size. With the neo gen it's easy. I had to de-rate my ferrite 3.2 meter because it wouldn't furl running at too high of a rotor speed. With this one I won't need to over-speed it to get the voltage I want from it to be able to do this, and at 30 mph those 3.2 meter blades got 4.1 kW available at the shaft.
Rather than de-tuning it, I want to build one that can run balls out just to see how much you can really get from a 10.5 foot turbine. :)
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Chris
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Chris - serious question.
If you're building turbines that can run balls-out all day and not explode or catch fire, have you considered doing away with the furling tail and all its attendant complexity, cost and weight, and making downwind units?
For a modest increase in weight/complexity/cost, you could put a disc brake on it to stop it in the event of a major blow.
Just seems to me that with "tough as nails" turbine assemblies and control gear, and something to *DO* with all the power, the tail is just unnecessary clutter and one more thing to fail?
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My last long term wind genny I had in the air was a small 6 footer zubbly style motor conversion that had no furling, and ran out full speed. It did end up failing in a spectacular fashion, but it took many unbelievable winds in stride. If I remember right we were topping 120 mph gusts in a massive storm to take it out. The genny was an approx 600 watt in strong winds, it was made from a motor that was originally a 1/2hp motor rewound.
When outside you used to hear that thing in high winds making sounds that would scare just about anyone, but it took it in stride.
With some integration of a 1:1transmission and a heavier shaft, the genny would have survived the blade coming apart, and it would likely still be out there today. The transmission loss would have been negligible as far as losses I would think given I would rather it still been alive making some power.
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If you're building turbines that can run balls-out all day and not explode or catch fire, have you considered doing away with the furling tail and all its attendant complexity, cost and weight, and making downwind units?
I have considered eliminating it as a furling tail and just place the turbine inline with the yaw as an upwind unit.
I think I'm to the point where I'm reasonably comfortable with controlling the turbine with electronics. Using a very robust generator with gearing provides greatly enhanced control over rotor speed even in very high winds. After I test and tune this one, if it works as expected, it will not need a furling tail and still be able to bring the turbine under control and stop it at 70 mph wind speed, with just the generator, with no damage to it.
When you can use PWM to drive your clipper, using a grossly oversized three-phase clipper load, you can bring a speeding turbine under control very gently with the PWM. And at the same time, match shaft power to the clipper load using the PWM at virtually any speed.
Once I achieve that, you'd better believe that furling tail will be gone and replaced with an emergency parking brake for wind speeds over 70 mph.
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Chris
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With some integration of a 1:1transmission and a heavier shaft, the genny would have survived the blade coming apart, and it would likely still be out there today. The transmission loss would have been negligible as far as losses I would think given I would rather it still been alive making some power.
Wolv,
The transmissions I build are 95.5% efficient at cut-in and 94.8% efficient at 3.3 kW input power. What that equates to, basically, is 8 watts loss at cut-in speed, mostly due to viscous drag from oil on the chain. At 3.3 kW input it equates to 172 watts loss in the drivetrain, and about half of that is due to the extra set of bearings you have to run when you have two shafts as opposed to one.
On a smaller rotor where you would only have say 1 kW input power, then the efficiency is right at 95%, meaning you'll lose 50 watts in the drive.
There is no "free lunch" with gearing - you have to trade torque for speed to make gains in gen efficiency to get it to work out to a positive net gain. And I think the smaller the rotor, the harder it is to justify using gearing on it.
On these very high voltage turbines I'm building now, it's a hands-down no-brainer to use gearing. There is no way to build generators that put out 180 volts at only .47 ohm resistance @ 400 rpm without gearing, and still get the coils to fit in the stator.
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Chris
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With some integration of a 1:1transmission and a heavier shaft, the genny would have survived the blade coming apart, and it would likely still be out there today. The transmission loss would have been negligible as far as losses I would think given I would rather it still been alive making some power.
Wolv,
The transmissions I build are 95.5% efficient at cut-in and 94.8% efficient at 3.3 kW input power. What that equates to, basically, is 8 watts loss at cut-in speed, mostly due to viscous drag from oil on the chain. At 3.3 kW input it equates to 172 watts loss in the drivetrain, and about half of that is due to the extra set of bearings you have to run when you have two shafts as opposed to one.
On a smaller rotor where you would only have say 1 kW input power, then the efficiency is right at 95%, meaning you'll lose 50 watts in the drive.
There is no "free lunch" with gearing - you have to trade torque for speed to make gains in gen efficiency to get it to work out to a positive net gain. And I think the smaller the rotor, the harder it is to justify using gearing on it.
On these very high voltage turbines I'm building now, it's a hands-down no-brainer to use gearing. There is no way to build generators that put out 180 volts at only .47 ohm resistance @ 400 rpm without gearing, and still get the coils to fit in the stator.
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Chris
What size are the rotors for this one?
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They are 255 mm with 2 x 1 x .5 N42's
[attachimg=1]
[attachimg=2]
This is the same generator as the 12G turbine has, except running at 1,300 rpm on this one, and five more turns of wire in the stator. This one has .343 gears in it.
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Chris
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Notice 1:1 ratio.
Maybe not so much a transmission, as a larger shaft in bearings, with a rubber or padded joiner connecting the two in a strait line.
This would be because the motor shaft was extremely lightweight for the job it was doing.
Any which way I like the way you setup your bearings, and an adaptation of this would have saved the alternator. I am not sure if its because I have the access to mills, lathes etc, but I don't find that it would be to incredibly hard to replicate a design like Chris has. I am sure there are things I do not know about it, but with work, and maybe a couple tries I am confident I could pull it off. I'm reasonably sure there are a few here also that could if they set out to do it.
Not to say Chris's design isn't something set apart from the ordinary.
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Not to saying Chris's design is not something apart from the ordinary.
I've read that a bunch of times, and too many double-negatives for me to comprehend!
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yeah,. I do that a lot. seems that growing up in a multiple language family screwed me up.
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Well, on all my other geared turbines I built weldment gearcases out of sheet steel like this:
[attachimg=1]
I found a piece of 3 x 6 x 1/4" wall rectangular tubing and cut off 10" of it. The big cog barely fits in it:
[attachimg=2]
Bore a couple holes thru it for shafts, weld a bottom on it, weld a flange to the top for a cover, and I got a gearcase. It'll work mint and save a lot of welding.
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Chris
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Chris
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That will be an exciting machine to be near .... 700 rpm is getting very exciting
No matter what else I may say, you do nice work. I like the box section for the g/box.
Will it float between buck to heat, or buck and heat simultaneously?
..................oztules
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Oz, I will program the power curve in the controller to let it run the turbine at 475 rpm @ 147 volts, or about TSR 6 @ 30 mph. The controller begins to unload the turbine from the DC load if one of two things happens:
- The amp limit you set in the controller is reached (I have this set at 84 amps presently).
- Either absorb or float stages of charging are reached.
When the controller unloads the turbine from the DC load due to one of the above the Aux 2 output of the controller switches the turbine over to the three-phase load with PWM driving a SSR. It regulates the voltage at the 147 volts. If it can't hold it at 147 due to excess turbine output (wind speed in excess of 30 mph) it will go over the controller's input voltage limit of 150 volts. The controller then goes into what is called "HyperVOC". In HyperVOC the controller stops charging batteries and the load is totally switched over to three-phase.
When the input voltage again drops below 150 the controller starts charging batteries again.
At 40 mph wind speed the turbine should not actually exceed 500 rpm, as the harder it tries to turn as the wind picks up, the load of the three-phase water heating increases faster than shaft power and stalls the rotor. I'm setting it up to furl between 35-40 mph with the rotor running on the bottom end of it's useful power curve (~ TSR 5).
If I would let it scream to 700 rpm by not having a heavy duty enough three-phase heating load, it would indeed be an interesting machine.
The first turbine taught me about how the controller works and I found you can't blow it up by running it over voltage or over amping it. boB and Robin have been in the business long enough to know better that to let that happen. This one is being designed to be able to take better advantage of the turbine's ability to heat water with high-voltage three-phase power, and the controller's ability to switch it back and forth and "blend" both the DC and AC loads as needed to control the turbine's speed.
Many times, what happens is that with both solar and wind the bank will reach float by noon and then the turbine is heating water all afternoon. The solar controllers regulate the bank at 26.5 volts and the bank and inverter loads can't even come close to using full turbine output. So rather than running the heater elements with inverter power like I do with my other turbines, why not heat water direct with the three-phase power off the turbine? You can heat a lot of damn water with 3 kW all afternoon - probably more than we can use in a day, and we got two 55 gallon water heaters to store it. That's why I'm doing this one this way.
I got one element controlled by the thermostat and that one runs off inverter power. That one insures that we always have at least 25 gallons of 125 degree water in the primary water heater. I got the other three elements (bottom in the primary heater and both in the pre-heater) wired delta for the clipper load.
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Chris
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Sounds like a plan.
When I played with resistive loads, I found that the thing runs away, and as it passed 5kw or more... I wanted to as well.
My problem was that the furling didn't behave as I expected it to..... and it just didn't furl. I don't know how far it went past 5kw, as the amp gauge was pinned to the end, and the voltage was heading past 150 from memory.
I think DaveB mentioned a change in furling behaviour..... but that was after I found out the exciting way. Direct shorts at over 5kw didn't bother the mill... (yet another failed experiment) but it sure bothered me.. ;D
Will be interested in the eventual outcome.
...............oztules.
What made it more exciting is that it was on a 3 meter pole/tower, and a bit close for comfort.... There is a write up somewhere of one of the times. If you saw the write up my chainsaw blades, you may note the myriads of knots in the crummy pine.... and that introduced more than a bit of doubt as well.
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@ oztules
I am interested as to what kind of resistive loads.
ie where these loads significantly increasing in temperature and lowering in resistance as the temp rose?
This could lead to missing the math involved with that change, therfore creating a sense of unpredictability?
Just a wild guess, I would not expect you to make simple oversites.
In extreme conditions Chris' setup with the water heating may do such, but its less likely as the temperature would generaly limit at the point water starts to boil. ( then you have other problems to worry about ).
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I got my three-phase load at 4.8 ohm so it will pull about 6.4 kW @ 175 volts. I think the key is using the PWM and the SSR to drive the load so it matches shaft power. I were to slam that load in fully, even in high winds, it would hard stall the turbine. If I get that little 3.2 meter putting out 6.4 kW, about all I can say about that is that she's flat out wound, baby. At that point I think I'm more worried about flying trees and buildings,and stuff like that, than flying turbine blades :)
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Chris
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Wolv
"
I am interested as to what kind of resistive loads.
ie where these loads significantly increasing in temperature and lowering in resistance as the temp rose?
This could lead to missing the math involved with that change, therfore creating a sense of unpredictability?
Just a wild guess, I would not expect you to make simple oversites."
Yes the R could increase with temp, but that is not what was happening.
The R was a few microwave primaries..... in a bucket of water for cooling... (turned out to mean boiling)
No the problem was that I was thinking the furling would be the same... it's not.
Think about it, W=ExI.... but E=IxR.... so W=E^2/R.... even if the R changes a bit, and the E rises to keep the W the same, it is still really a square function. So for a given R load, it will absorb power as a square of the rpm, but the wind see things differently..... its power is a cube of the rpm...... therein lies the problem.
So unless you pick a monster load, and use PWM as Chris is going to do, you will be overpowered by an order of magnitude.... simple.
I knew that, and knew R may change, but inconsequential really, it was the furling that changed that made it so interesting. I know from experience that 4 ohm load on my mill is just no where near enough to try this with pwm mitigation, probably 2R might work. ( the two coils were about 4R from memory... total.)
As DaveB explained, is's the furling you need or more loads to switch in... one of the two (or more pwm into a huge load .. per Chris)
I'd like to claim some other losses from the inductive reactance of the coils to the frequency.... but that would be wishful thinking. Air coils in the mill stator would have the same problem.... and they didn't exhibit any lack of ooomph.
..................oztules
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In extreme conditions Chris' setup with the water heating may do such, but its less likely as the temperature would generaly limit at the point water starts to boil. ( then you have other problems to worry about ).
I've long heated water with the turbines and solar as a "dump load", except running the elements with the inverter. When I first started doing that on a couple good days of wind we blew the steam valve on the primary water heater twice. My wife was PI$$ED! It blew hot water all over her laundry room. The pipe blow-off pipe goes down towards the floor but when it blew it still sprayed water everywhere.
That was when I put the elements on thermostatic control, bought another RD-1 and use the second RD-1 to shut down the turbines when the system voltage goes over 30.
This three phase water heating is using the same elements I used before. I'm still experimenting with it and the ferrite magnet turbine doesn't make as much voltage as I'd like to get better efficiency from it. When I get this new rig flying it should be more efficient and do a better job of water heating.
Even so, with the wind blowing today the little ferrite 3.2 meter has been heating water since about 11:00 this morning. It's got the primary heater up to 175 degrees and the preheater up to 115 degrees. We'll take showers tonight and that'll use a bunch of hot water up. But when it gets that hot you don't use much and you have to be really careful not to get accidentally burnt by it.
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Chris
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For reference I replied to this here, as it was of similar topic
http://www.anotherpower.com/board/index.php/topic,278.msg2289.html#msg2289 (http://www.anotherpower.com/board/index.php/topic,278.msg2289.html#msg2289)
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It's got the primary heater up to 175 degrees and the preheater up to 115 degrees. We'll take showers tonight and that'll use a bunch of hot water up. But when it gets that hot you don't use much and you have to be really careful not to get accidentally burnt by it.
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Chris
No tempering valve? You can get a hefty fine for that here in NZ...
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No tempering valve? You can get a hefty fine for that here in NZ...
The day some government agency thinks they can tell me what to do or not to do in my own home - and if I don't do what they say I'm going to get fined - is the day I'll be grabbing the 12 gauge and heading to City Hall to fix the problem.
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Chris
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I agree Chris, but it seems there are to many sheep that just follow orders.
Hopefully thre are more of us out there than I realize.
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The only thing that comes to mind with that is that whole thing about "biggah baddah boom!"
I'm sure I don't have to tell you man... them watur heeterz thar aint no joke!
What about an electronic valve to release some of the hot water elsewhere when the tank temp gets close to (but not quite at) the trip point of the TPRV?
Meter off a few gallons (or even just do it by time) by something like a hose leading somewhere that it won't matter when some 170 degree water suddenly shows up?
Just a thought...
Either way, just be careful dude.
Steve
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Something I do here, which may not be conventional... I monitor the upper manifold temperature, and when it gets to a setpoint of my choice, I actually pump off a bunch of the heat into my hydronics tanks. It has the benefit of cooling the solar collector so it won't blow off and waste energy, while putting it somewhere I can use.
I still have the external pressure relief valve of course, but it's set quite low (it's not a mains-pressure system).
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I still think in these kind of things the KISS method ( at least as a last resort device) is best.
I have had some training in steam engines.
The first thing said and stressed over and over.
All safety devices are there for more than show, these are what keep you among the living.
Make sure above all else they are working before starting any boiler, they HAVE to be the first thing to fail!
Electrical control is great, as long as there is a mechanical fail safe device for the just in case moment.
One that is testable so its demonstrably able to rely on. and then don't always rely on that.
Even if this is just a weak material pipe in a safe to vent area.
This likely does not carry as great of dangers but it does have some.
I also would suggest electrical control should be built so if it fails, it fails to be as likely to go to an off state as best possible, so no power to anything that heats.
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I like Ross' idea of pumping off hot water. If we had a hydronic heating system that's what I'd do too. Since I hooked up my three elements for three phase water heating I got the thermostats set on them at 185 degrees. I haven't figured out a good way to deal with that yet. The primary heater is always hotter than the pre-heater. If the primary gets up to 185 and shuts the element off, then my three-phase load goes away.
I can configure one of my RD-1's for a temp input signal on one channel. Then use it to shut the turbine down at 180 degrees or whatever. But so far I haven't done that - I've been simply monitoring it and having my wife run some hot water to wash clothes or dishes if if the primary heater gets too hot.
We got that problem today, actually. The wind died down for a bit last night and switched from SE to W. It came back with a vengeance at 25-30 mph and the bank has been floating for 25 hours now. That primary heater was up to 172 when I came in for lunch so my wife is doing laundry to use it up and cool the heaters off. She uses "warm" water on the washer setting and it's steaming hot. But it sure got my dirty coveralls nice and clean. Nothing like good hot water to remove dirt :)
If the wind continues to blow I'll have to shut the turbine down.
Edit: I just got an idea after I posted that. Why couldn't a guy put one of those Modine heater exchangers like they use with outdoor wood boilers on it? Just plumb the thing into the hot water line with a circulation pump and a thermostat to turn it on if the water gets to 180. Plumb the return into the cold water in on the water heater.
That would be useful for winter time. Wouldn't work all that great in the summer. But it's usually only in the winter when we get these sustained high winds anyway.
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Chris
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That water-air exchanger sounds like a good idea to me.
It seems I am always looking for a way to get some heat from a cheap source here in Mn.
How would you move the water thought the exchange that is both tolerant of the heat, and still potable?
Is there any way to be assured the metals, and solders are also usable in a potable water system?
I'm sure there are a few things to consider like the galvanic corrosion possibilities if you have some way out water ph conditions.
I'm sure this is less of a worry to what hard water could do over time.
But really neither of the last two are a big deal I would guess, just figured for point of discussion I would mention them.
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Maybe adding a secondary water/water exchange system and/or yet another heating tank just for this use may also be an option?
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Just hit me -
Chris, wasn't it you that was mentioning that your solar panels aint worth squat in the dead of winter due to ice? Was either you or Ross...
Anyway, the heat exchanger sounds good, but to extend that idea, what about running some plumbing up behind the panels (assuming on the roof) to help eradicate some of the ice problems?
I don't know how feasible that really is to actually implement, but from an "on paper" perspective, it seems plausible.
Probably would need to be a closed loop system that carries the actual heat to the roof, with glycol (or something) as an antifreeze for when the pump isn't "dumping".
Just seems like since the extra energy needs to be dealt with anyway, why not make it do something useful in the process?
Of course, it's kinda counterintuitive, doing something with excess energy that will only end in even more energy production, but what if the wind dies down on you for a couple days, but your panels were thawed out ahead of time? ;)
FWIW
Steve
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Just hit me -
Chris, wasn't it you that was mentioning that your solar panels aint worth squat in the dead of winter due to ice? Was either you or Ross...
Wasn't me - I get great output in winter. But then, I don't get within half a degree of absolute zero like Chris does :)
(I also don't generally get ANY snow, much less 18 feet of the stuff!)
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Anyway, the heat exchanger sounds good, but to extend that idea, what about running some plumbing up behind the panels (assuming on the roof) to help eradicate some of the ice problems?
It was me. We're getting well past the winter solstice now and the panels are starting to work again. We got 6" of snow yesterday and I didn't bother cleaning them off because the sun wasn't shining and the wind was blowing at 30 mph. When the wind blows at least 12 mph steady I have no use for the solar panels.
But today the wind died out and the sun came out for a few hours. The panels worked good today and we got 8.7 kWh from them.
The problem isn't really snow and ice so much as terrible solar conditions from about the first of December to the middle of February. As the days continue to get longer now the solar starts getting pretty reliable again. But compared to yesterday during the snow storm when I got 48 kWh from wind turbines (and 54 kWh the day before), 8.7 kWh today is like a drop in the bucket. It's enough to get us thru until the wind blows again without the generator having to start.
The solar panels are our "backup" for poor wind days.
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Chris
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The genset is where the idea mostly came in - I remember you mentioning having to go out in very undesirable conditions to start the thing because your inverter (and therefore blower) cut out due to LVD.
I guess the question then becomes, does the labor and cost of installing something like this outweigh the dreaded 3AM genset cranking in sub-zero temps?
In the summer (or when conditions otherwise aren't conducive to releasing the heat there), the heat could be diverted to the heat exchanger (assuming water to air) mentioned before.
I figure the energy needs to go somewhere... so why not? :)
Steve
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I guess the question then becomes, does the labor and cost of installing something like this outweigh the dreaded 3AM genset cranking in sub-zero temps?
Well, we've upgraded our system drastically since those days ;)
We put in a whole new system last April, and we're loving it. Our generator starts by itself now, when required. It's got cold weather pre-heat that comes on automatically when the ambient temp drops below 5° F, and the whole nine yards. We had somewhat of a cobbled together system for close to 8 years. When our daughter graduated from college we decided to spend some money on ourselves for once. These days, if it gets down to -20F and we run short on power at 3:00AM we just stay in bed where it's nice and warm, and the generator is also nice and toasty warm and it starts up and takes care of the problem. ;D
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Chris
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I've had this new turbine completed, test run and ready for the tower for over a week. Just waiting for weather so I can lower the tower, get the 3.8 meter off it and install the new one.
We had a blizzard a few days ago that left a sheet of ice 2-3" thick were the winch truck has to park to hold the tower, and snow so deep it's over my waist where the tower lays down. Might be a bit before I'll be able to get that tower down.
(https://lh4.googleusercontent.com/-CwEzXLXRDZM/T1LcOks3QJI/AAAAAAAAF7o/4OhINfrMrMY/s640/100_1438.JPG)
(https://lh3.googleusercontent.com/-1x1ImUxy5vs/T1LcQuX-03I/AAAAAAAAF74/whk3lDWwSBw/s640/100_1440.JPG)
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Chris
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As long as I haven't been able to get this machine on the tower when I wanted to, might as well go over some of the other "features" I built into this one.
I've never had a need to change oil in the gearcase on any of these geared turbines, and the oldest one is over 2 years on the tower and about 16,000 hours running time on it. The last time I had that one down, which was last summer, it still hasn't developed any backlash in the drivetrain, it runs quiet, and still has the original oil in it that was put in when it was built in November of 2009.
But I figured what the heck. On this one I put in a drain plug on the side of the gearcase that faces the ground when the tower is lowered, and the drain plug is at the lowest point in the sump:
(https://lh6.googleusercontent.com/-GlZFTlqz9TM/T1LugzKwlcI/AAAAAAAAF8M/Mf7KWHMh4mM/s640/100_1441.JPG)
And then I put in a fill plug on the other side of the gearcase - this particular transmission design requires 250cc of oil in it. I didn't bother putting a brass washer on the fill plug.
(https://lh4.googleusercontent.com/-__eJUKPZrZE/T1LuhIMljhI/AAAAAAAAF8g/iH56AJ_iU4c/s640/100_1442.JPG)
On the last two turbines I've made these smoked Lexan generator shrouds. They help to keep the weather out of the generator (especially snow and ice). And they look really nice too
(https://lh6.googleusercontent.com/-8wj73OxDcSg/T1LuhQjevQI/AAAAAAAAF8Y/G_vYaYSCkIM/s640/100_1443.JPG)
I used the same type of stator mount that I used on the ferrite machine. There's a steel bushing in the stator that prevents crushing or cracking of the stator, and a spacer with two stainless steel washers on the end of it. I used five 3/8" bolts on this one and they are torqued to 45 lb-ft. The old "threaded rod mount" in the book designs is bogus because they come loose after awhile - it don't matter if you use loctite on the nuts or not. They still come loose. This setup will never loosen up and ruin a stator because the nuts came loose
(https://lh6.googleusercontent.com/-X9kljBMgF70/T1Luh4dYdSI/AAAAAAAAF8s/sV1PLUeeYLE/s640/100_1445.JPG)
On this stator I brought all six leads of the three phases out in the form of power studs cast integral in the stator. I have it wired wye for this high voltage application. But I can also wire it IRP or delta if I want. I've built some stators that are hard wired internally delta or wye. But it's always best to bring all six leads out like this in case you want to change something in the future
(https://lh3.googleusercontent.com/-Qpx6oL1usYI/T1LuiGdQ21I/AAAAAAAAF80/msJgyalWsK4/s640/100_1446.JPG)
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Chris
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And then I put in a fill plug on the other side of the gearcase - this particular transmission design requires 250cc of oil in it. I didn't bother putting a brass washer on the fill plug.
Chris
Chris, how did you determine how much oil to use in the gear case?
Also, excellent job on the wind turbine, very professional.
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Chris, how did you determine how much oil to use in the gear case?
The inside of the gearcase measures 14 cm x 6.4 cm and requires an oil depth of 2.8 cm for the very bottom of the chain to be submerged in oil. That's 250 cm3.
Edit: When these things are running the chain acts as an oil pump and it pulls the level of the oil down in the sump to where the chain is running in no oil. The oil is carried to the top by the chain where it gets flung around in the gearcase in a fine mist by the high speed shaft, that can be spinning up to 1,200 rpm. The oil drains back down the case walls to the sump where it gets picked up again.
The viscous drag in the drivetrain is virtually zero. The gearcase is 95.1% power efficient @ 112 rpm input, 94.8% power efficient @ 475 rpm input @ 4.1 kW.
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Chris
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Very nice machine, Chris.
I think you have effectively killed off the idea that geared mills are a bad thing. Nice work. ;)
Hopefully the weather works with you and you can get it in the air, looking forward to seeing some data from this.
Oh, and power too... :D
Steve
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Really, I don't know who came up with the theory that geared mills are "bad". Gearing has been used in wind turbines for better than 80 years. From the Winchargers built in the 30's to the modern Vesta turbines built by the largest manufacturer of wind turbines on earth.
There's a lot of "old wive's tales" that seem to get propagated as "fact". For instance, I read in a book called "Homebrew Windpower" once that using springs on the tail of a wind turbine is "bad". It says in the book, quote, "the spring could break and cause your turbine to fail". And yet I read recently where the tail on a turbine failed because it didn't have a spring in it to dampen it. Ironically, the turbine that failed is owned by the author of that book.
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Chris
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Hi Chris, Just wondering if you put slip rings on your units so as not to have to worry about wire twisting coming down the tower?? I was thinking that is something I would do on my turbine..Does this make good sence to you or is it not necessary.. I know on my unit I built over 20 years ago I had slip rings on it.. Thanks for your expertise and this great site!1 Duff,,, Bio Diesel Man
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No, I just use a hanging Type SEOW cable. I try to avoid slip rings like the plague.
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Chris
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Really, I don't know who came up with the theory that geared mills are "bad". Gearing has been used in wind turbines for better than 80 years. From the Winchargers built in the 30's to the modern Vesta turbines built by the largest manufacturer of wind turbines on earth.
There's a lot of "old wive's tales" that seem to get propagated as "fact". For instance, I read in a book called "Homebrew Windpower" once that using springs on the tail of a wind turbine is "bad". It says in the book, quote, "the spring could break and cause your turbine to fail". And yet I read recently where the tail on a turbine failed because it didn't have a spring in it to dampen it. Ironically, the turbine that failed is owned by the author of that book.
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Chris
That's the kind of thing I would be referring to... several posts "over there" that seem to be off with a few things... ???
But as I read more and more, the forward thinking seems to dispel the rumors. While it's true that there are losses in something like gearing, it's apparent that at and above certain sizes/power levels, the losses are overwhelmed by the gains.
I've always kinda wondered why "they" were so intent on not doing such things; as you said, every commercial grade turbine above a certain power level has a tranny in it. There had to be a reason that they kept using them. So why that's "beyond" the DIY crowd has always kinda bothered me. Maybe it's fear for the extra complications involved... ?
Now, granted, I speak from a purely theoretical point of view; I've never built a wind turbine (of any real size anyway) for myself, so I can't give personal experience on the pros and cons of doing so. But logic dictates one does not use a tire iron for a toothpick, and a small sliver of wood to manipulate rubber on a metal rim. ;)
Steve
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MadScientist267,
My last turbine (iron genny) weighed in at a little less than 100 pounds without a gear box IIRC. I will have to lighten it in other areas to keep the weight down if I add one as I prefer not to have too much money tied up in equipment or rental to lift it in place.
Gear boxes take more attention to detail to get them right. That takes them out of the scope of most backyard hobbies unless they have a small machine shop in their garage. I think that may have been where no gear boxes thing originated and a little more and more was added as time went on.
Springs, IMHO, have to be quality as well as set up correctly if they are going to work without constant replacement.
I'm thinking that once the commercial turbines get to a size that is unmanageable by human muscle, the manufacturers realise that and they add the additional weight of a gear box, and thereby adding efficiency without compromising sales. The largest turbines on the planet, arguably, have the highest efficiencies.
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I've always kinda wondered why "they" were so intent on not doing such things; as you said, every commercial grade turbine above a certain power level has a tranny in it. There had to be a reason that they kept using them. So why that's "beyond" the DIY crowd has always kinda bothered me. Maybe it's fear for the extra complications involved... ?
Not every utility scale turbine uses gearing. There are a few, such as Enercon, that use direct drive. But the size and weight, complexity and cost of the generator is significant in those machines.
The homebrew book designs were developed to be easy to build from commonly available materials, using normal hand tools, and not requiring any significant machine work. But just because that's one way to build a simple turbine does not mean it's the only way. And that's where the homebrew books got it wrong - they attempt to give a person the notion that anything more complex than the simple way is going to break, or fail, or it won't work. That's dead wrong thinking. In this case I invite somebody to try and design a direct drive 180 volt generator for a 10 foot turbine that operates at better than 90% efficiency at 3 kW output. Attempting that will immediately bring to light the limitations of one design, that are not limitations in another.
When ever you build a high performance machine you have to take some pictures of the engine because it might have a 12-71 blower and Enderle injection or something:
[attachimg=1]
Well, this one isn't nearly that exciting. But this is what ultimately will make everything happen on this new turbine when I get it up:
(https://lh3.googleusercontent.com/-O_kfWTIJ5oo/T1OmtvcNWBI/AAAAAAAAF9Y/MHQEDv2kw6k/s640/100_1454.JPG)
(https://lh3.googleusercontent.com/-srcNYE6A7PA/T1OmugA5nqI/AAAAAAAAF9w/DNYNewhbSQs/s640/100_1457.JPG)
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Chris
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I think "K.I.S.S" trumped everything there? The same attitude that let the forum go with no changes, guidance or care for years drives K.I.S.S. there? I call it apathy.
Simple is good but only if it works and works long term.
I don't build turbines but I probably could build a dual rotor Hugh Piggott style unit if push came to shove.
Not even remotely capable of a transmission build myself.
So it kind of comes down to what you are capable of.
Now if there was a junk yard component that would sub in for the hand built transmission then it might suit more DIY types?
Frankly, I see both sides to this and could argue either effectively in a debate.
Things tend to favor gearing when the size exceeds 20 feet or so. Or seems to anyway.
Courses for horses as they say.
Tom
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Things tend to favor gearing when the size exceeds 20 feet or so. Or seems to anyway.
Gearing is more common in 20 foot and larger. But Wincharger used it on machines down to 6 feet in diameter because neo magnet technology didn't exist back then and they needed speed to get their 6 volts.
I can be practical anywhere you get gains in overall efficiency by using it. The gains might be economic - magnet and copper cost vs cost in the gearbox. They might be electrical - better power efficiency while taking a "hit" in gearing vs a direct drive.
There are always going to be folks that proclaim direct drive as "the only way", and I assume those folks own cars with the engine strapped sideways in the trunk with a tire bolted to each end of the crankshaft. It all depends on the application and the design. For a small 10 foot turbine like this on a direct hooked battery charging configuration I suspect it would be hard to justify a geared mill. For a high voltage application where I can live with a few losses in gearing to get greatly enhanced output it pays off.
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Chris
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I think "K.I.S.S" trumped everything there?
Simple is good but only if it works and works long term.
Not even remotely capable of a transmission build myself.
Yes. KISS. And KISS works.
Not many people can build a "works long term" transmission, leaving KISS.
For a small 10 foot turbine like this on a direct hooked battery charging configuration I suspect it would be hard to justify a geared mill.
and
Really, I don't know who came up with the theory that geared mills are "bad".
There's a lot of "old wive's tales" that seem to get propagated as "fact".
And that perspective is Exactly where it came from!
Just a few years ago, before your time in the discussions, 4' was small, 6~7' was big, and 10' was huge.
Now, 4' is a toy, 6~7' is tiny, and 10' is small.
A 10~20~50 year old book is going to have a different perspective of something small or large, and DIY.
When neos did not exist, or when neos and copper were cheap, the perspective will be different.
Apples : Oranges
(my uncle used to brag that his pickup truck got 11MPG)
G-
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Looking purely from the perspective of using what is available, would it be viable to use a cam chain and sprockets from something before the era of the cambelt?
The sprockets on the (small) engines I have experience of would generally have the cam sprocket on the flush end of the camshaft but the crankshaft end would be through hole with a key or splined.
Just making a mind exercise working backwards from the items maybe available from the local scrap merchant!!
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Looking purely from the perspective of using what is available, would it be viable to use a cam chain and sprockets from something before the era of the cambelt?
I suppose it could work. But you only have one gear ratio option with that - .5:1. The crank sprocket is keyed and usually has a non-standard bore size, which is going to require machining a shaft to fit both the bearings and the sprocket bore. And a cam sprocket has no set screws meaning you'll have to machine spacers to "clamp" it in place like it is when the harmonic damper is bolted to the crank nose.
The cam sprocket is typically bolted to the camshaft with three or four bolts (depending on the engine it came from) and the center pilots on a boss on the front face of the camshaft. That will also require some machining.
Really, I think it's easier to use machine sprockets which come in standard bore sizes, have set screws to lock them place, and are cheap. It's only about $30 for a machine sprocket set with hardened teeth on the small one.
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Chris
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Just a few years ago, before your time in the discussions, 4' was small, 6~7' was big, and 10' was huge.
Yes, I suppose that's true. But I see that the larger homebrew mills are not safe or practical too. So the design has to change. For instance, the "Otherpower 17", to my way of design, has a generator that's good for 2,500 watts continuous output strapped to a rotor than can easily develop 10 kW. They build these things and burn 'em up. So then they throw another in-hand turn in it to "beef it up" and it's still woefully inadequate. And this design methodology has been "sold" to the unsuspecting newbie turbine builder as a "solid design".
When I look at it, there is nothing "solid", or even remotely good, about a 17 foot turbine with a grossly under-powered generator protected by a furling system that might work and might not, with the whole thing spinning on a frickin' trailer spindle that has an outer bearing with barely a 1" bore in the inner race. About all I can say about that design is that it's damn good thing the people that designed it don't build bridges and tall buildings.
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Chris
Edit:
When I look at it, there is nothing "solid", or even remotely good, about a 17 foot turbine with a grossly under-powered generator protected by a furling system that might work and might not, with the whole thing spinning on a frickin' trailer spindle that has an outer bearing with barely a 1" bore in the inner race.
Oh yeah - and to top it off the whole contraption is held on the tower by a Jesus Nut with a cotter pin thru it.
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Yea, I'm sure glad I didn't go that direction and keep scaling up a smaller turbine.
I also don't need the swept area like you and it just seems ridiculous to put up such
a large rotor and pray for the best. ???
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Just a few years ago, before your time in the discussions, 4' was small, 6~7' was big, and 10' was huge.
Yes, I suppose that's true. But I see that the larger homebrew mills are not safe or practical too. So the design has to change. For instance, the "Otherpower 17", to my way of design, has a generator that's good for 2,500 watts continuous output strapped to a rotor than can easily develop 10 kW. They build these things and burn 'em up. So then they throw another in-hand turn in it to "beef it up" and it's still woefully inadequate. And this design methodology has been "sold" to the unsuspecting newbie turbine builder as a "solid design".
When I look at it, there is nothing "solid", or even remotely good, about a 17 foot turbine with a grossly under-powered generator protected by a furling system that might work and might not, with the whole thing spinning on a frickin' trailer spindle that has an outer bearing with barely a 1" bore in the inner race. About all I can say about that design is that it's damn good thing the people that designed it don't build bridges and tall buildings.
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Chris
Edit:
When I look at it, there is nothing "solid", or even remotely good, about a 17 foot turbine with a grossly under-powered generator protected by a furling system that might work and might not, with the whole thing spinning on a frickin' trailer spindle that has an outer bearing with barely a 1" bore in the inner race.
Oh yeah - and to top it off the whole contraption is held on the tower by a Jesus Nut with a cotter pin thru it.
Are you saying the rotor as it is designed for the otherpower 17' turbine lacks in power to drive the generator?
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Are you saying the rotor as it is designed for the otherpower 17' turbine lacks in power to drive the generator?
Quite the opposite.
I think he's saying
has a generator that's good for 2,500 watts continuous output strapped to a rotor than can easily develop 10 kW.
Ie, the rotor (blades and hub) can easily develop 10kW, however the generator maxes out at 25% of that, so in a good blow the generator burns up rather than keeping the rotor under control.
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Yea, I'm sure glad I didn't go that direction and keep scaling up a smaller turbine.
I also don't need the swept area like you and it just seems ridiculous to put up such
a large rotor and pray for the best. ???
I did go that way and burned up 6 stators before putting iron in them. That seemed to help keep the stator cool in turbulent winds.
The tapered roller bearings needed adjustment monthly on the seven I have built so far.
I still think the 'smaller' ones are good for a first build. It made the cogs turn. Windstuffnow had some good builds. He didn't try to make a 17 footer either. They don't scale up well IMHO.
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Just a few years ago, before your time in the discussions, 4' was small, 6~7' was big, and 10' was huge.
Yes, I suppose that's true. But I see that the larger homebrew mills are not safe or practical too. So the design has to change. For instance, the "Otherpower 17", to my way of design, has a generator that's good for 2,500 watts continuous output strapped to a rotor than can easily develop 10 kW. They build these things and burn 'em up. So then they throw another in-hand turn in it to "beef it up" and it's still woefully inadequate. And this design methodology has been "sold" to the unsuspecting newbie turbine builder as a "solid design".
When I look at it, there is nothing "solid", or even remotely good, about a 17 foot turbine with a grossly under-powered generator protected by a furling system that might work and might not, with the whole thing spinning on a frickin' trailer spindle that has an outer bearing with barely a 1" bore in the inner race. About all I can say about that design is that it's damn good thing the people that designed it don't build bridges and tall buildings.
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Chris
Edit:
When I look at it, there is nothing "solid", or even remotely good, about a 17 foot turbine with a grossly under-powered generator protected by a furling system that might work and might not, with the whole thing spinning on a frickin' trailer spindle that has an outer bearing with barely a 1" bore in the inner race.
Oh yeah - and to top it off the whole contraption is held on the tower by a Jesus Nut with a cotter pin thru it.
Ross, That is not what I understand by what is in red.
And, in yellow to be if Chris designs the rotor to drive that otherpower generator.
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Ross, That is not what I understand by what is in red.
And, in yellow to be if Chris designs the rotor to drive that otherpower generator.
No, Ross is right. The generator in the Otherpower 17 (the latest version after the first one burned up) uses dual 14 in a 16/12 generator @ .3 ohm. At 50 amps the thing is dissipating 750 watts, or just about 25% of the total power input to it, assuming a bank voltage of 50 volts. That's hot. Plug in a 750 watt heating plate, or coffee maker, or what have you, and lay your hand on it if you want to see just how hot that is.
I would in no way shape or form put that weak-kneed of a generator on a 17 foot rotor that is easily capable of putting 10 kW to the shaft at only 30 mph wind speed. You have to understand with wind turbines that when I say "When I look at it, there is nothing "solid", or even remotely good, about a 17 foot turbine with a grossly under-powered generator" that the generator is what provides the braking torque for the rotor to keep it under control. A grossly underpowered generator does not develop enough braking torque to control the the rotor. So you have to rely on other methods, such as furling to reduce the swept area, or you'll burn it up.
Burnouts with the "otherpower 17" design are well documented by many folks who have built them and don't have thin mountain air to reduce the power thru the rotor.
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Chris
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Ross, That is not what I understand by what is in red.
And, in yellow to be if Chris designs the rotor to drive that otherpower generator.
No, Ross is right. The generator in the Otherpower 17 (the latest version after the first one burned up) uses dual 14 in a 16/12 generator @ .3 ohm. At 50 amps the thing is dissipating 750 watts, or just about 25% of the total power input to it, assuming a bank voltage of 50 volts. That's hot. Plug in a 750 watt heating plate, or coffee maker, or what have you, and lay your hand on it if you want to see just how hot that is.
I would in no way shape or form put that weak-kneed of a generator on a 17 foot rotor that is easily capable of putting 10 kW to the shaft at only 30 mph wind speed. You have to understand with wind turbines that when I say "When I look at it, there is nothing "solid", or even remotely good, about a 17 foot turbine with a grossly under-powered generator" that the generator is what provides the braking torque for the rotor to keep it under control. A grossly underpowered generator does not develop enough braking torque to control the the rotor. So you have to rely on other methods, such as furling to reduce the swept area, or you'll burn it up.
Burnouts with the "otherpower 17" design are well documented by many folks who have built them and don't have thin mountain air to reduce the power thru the rotor.
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Chris
Thanks for the clarification Chris.
Ross, no arguments, just needed clarification. I have one of those flying and with my built in blunders, no comment otherwise.
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When I look at it, there is nothing "solid", or even remotely good, about a 17 foot turbine with a grossly under-powered generator
Ross, That is not what I understand by what is in red.
Well, we might have to wait for chris to answer - but the way I interpreted it was that the generator was "under-rated" (my term) for the job. I think "under-powered" may have just been a poor choice of words. As in, "it is not powerful enough".
In more "conventional" motor-generator sets, if you have a motor that is capable of 10kW and an alternator that is capable of 2.5kW, you can never burn out the motor. Even pulling maximum out of the generator, the motor is only lightly loaded.
The difference with that is that the motor is only delivering the power it needs to.
With a wind turbine, the wind *IS GOING TO TURN THE PROP*. If it's 100mph wind, that prop is going to be SCREAMING if you don't have something to keep it under control. And the only way to keep it under control is to have enough load... and if the prop WILL make 10kW and the generator can only suck out 2.5kW, you're going to burn up the generator - or if it somehow survives, your prop is still likely to overspeed.
Edit: Doh! Was on the phone, hadn't hit enter. And now I see I'm two messages behind!
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Yes, in the commercial world of wind power a 17 foot machine will be typically rated at 6 kW output @ 12.5 m/s. This allows for a generator efficiency of slightly better than 75% at full rated power.
In the case of the "otherpower 17" if you ever did get it to that output, continuous, you have a disaster on your hands. Assuming you can drive your bank to 60 volts, you got 100 amps output with dual 14 gauge windings in the stator? Even my grandson knows that's not going to work.
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Chris
Edit: I would like to add that in the "real world" you'll probably have about 20 volts drop in the line getting the power from the gen to the battery. Ideally, with this turbine you should have 40 volts drop. So assume it's running at 100 volts at the generator @ 6 kW. It's still putting out 60 amps. That's way too much for dual 14 windings.
At 60 amps and .3 ohm it's dissipating almost 1,100 watts in the winding and you only got 3.6 kW output to your battery. From the input shaft to the battery you're losing a whopping 4,160 watts. This is why I don't consider much over a 12 foot wind turbine to be even remotely practical for battery charging. You're better off with two smaller ones.
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Yes, in the commercial world of wind power a 17 foot machine will be typically rated at 6 kW output @ 12.5 m/s. This allows for a generator efficiency of slightly better than 75% at full rated power.
In the case of the "otherpower 17" if you ever did get it to that output, continuous, you have a disaster on your hands. Assuming you can drive your bank to 60 volts, you got 100 amps output with dual 14 gauge windings in the stator? Even my grandson knows that's not going to work.
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Chris
Edit: I would like to add that in the "real world" you'll probably have about 20 volts drop in the line getting the power from the gen to the battery. Ideally, with this turbine you should have 40 volts drop. So assume it's running at 100 volts at the generator @ 6 kW. It's still putting out 60 amps. That's way too much for dual 14 windings.
At 60 amps and .3 ohm it's dissipating almost 1,100 watts in the winding and you only got 3.6 kW output to your battery. From the input shaft to the battery you're losing a whopping 4,160 watts. This is why I don't consider much over a 12 foot wind turbine to be even remotely practical for battery charging. You're better off with two smaller ones.
On page 268 of the " Homebrew Wind Power " book it does say it's a 3000 or more continuous watt turbine and peaks of double or more are possible from it. I only wish the wind blew hard enough around here for long enough to burn that thing to the ground. Then, I'd have a reason to put up one of yours.
In reality, for what it's used for and where it is placed, it does fine. I did make a few changes to it, bearings for one as well as magnet rotor diameter and 3 in hand 14awg copper. The copper was in fact a recommendation I got from fieldline members.
So, even though those plans were published, I have to respect that the Dans do admit and update as problems arise.
Edit: I said even though those plans were published, what I mean by that is: Because the plans were published, and because the Dans have included at least one acknowledged weakness, I respect the Dans for their updates.
I should also make a point to thank you too as well Chris for helping the rest of us that have not been fortunate enough to experiment and prove different ideas as you have. So, Thank you.
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On page 268 of the " Homebrew Wind Power " book it does say it's a 3000 or more continuous watt turbine and peaks of double or more are possible from it.
Yes, it's a poor wind site turbine. It would not survive two weeks here where I live. They make great power in lower wind speeds because of the swept area, and I suspect that's what drove the Dan's to keep trying to scale them bigger and bigger. They have thin air at 6,000 feet, which doesn't have much power in it. And they got turbulence thru the rotor because of the area they live in.
The other extreme is somebody that lives on the plains at 1,500 feet elevation and you can see for 40 miles in every direction. In Kansas you'd better have a wind turbine that's built like a tank or it won't make it thru its first afternoon.
Most folks live somewhere in between those two extremes. The folks that have built those and put them on good wind sites have had nothing but problems.
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Chris
Edit: I guess that can apply to any of the plains states. In Kansas the standard wind speed indicator is a length of log chain nailed to a fence post. If the chain is at 45 degrees to the post it's a light spring breeze. If the chain is standing straight out it means a real wind might pick up later. But I've been in North Dakota along I94 and US2 where if you stick a wind turbine up 30 feet in the air there's not much between that turbine rotor and the Montana and Canadian borders except wind.
The venerable Jacobs turbines are numerous in the plains states. And many of them have been running for better than 30 years.
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So, in all fairness then, would you consider it a true statement to say that the opposite applies as well?
A turbine designed for low altitude (pronounced "one of yours") would not perform as well as those designed for higher altitude (similarly, "one of theirs")?
Just curious how that works in terms of the dynamic of the relationship... to me, it's starting to seem that there's no right or wrong, it's what works for the properties of the geographic location one lives in.
How far off am I with this?
Steve
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They have thin air at 6,000 feet, which doesn't have much power in it.
The other extreme is somebody that lives on the plains at 1,500 feet elevation and you can see for 40 miles in every direction.
<RossBot> Density of 20.0 deg C dry air at 0 feet (1013 hpa) is 1.204 Kg/m^3
<RossBot> Density of 20.0 deg C dry air at 1500 feet (956 hpa) is 1.137 Kg/m^3
<RossBot> Density of 20.0 deg C dry air at 6000 feet (786 hpa) is 0.935 Kg/m^3
Applying those densities to the same turbine (17' DIA) in the same 30 mph wind, with the same generator efficiency (80%) and same coefficient of performance (0.2) sees:
30621.2 watts possible (4899.4 watts output)
28917.2 watts possible (4626.7 watts output)
23779.7 watts possible (3804.8 watts output)
That doesn't make any allowance for turbulence etc.
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So, in all fairness then, would you consider it a true statement to say that the opposite applies as well?
A turbine designed for low altitude (pronounced "one of yours") would not perform as well as those designed for higher altitude (similarly, "one of theirs")?
Just curious how that works in terms of the dynamic of the relationship... to me, it's starting to seem that there's no right or wrong, it's what works for the properties of the geographic location one lives in.
How far off am I with this?
Steve
It appears this way to me as well Steve. Where this turbine is located, approximately 2250ft and fair wind conditions, the only troubles I seem to notice, again self-made, come from stalling at around cut-in. This is more so dependent on battery bank voltage and the worst when the bank is around 50% SOC or lower.
I'm trying to build a 14.5' for my residence which I am in hopes to prevent runaway as well as control with a classic. We will see. He He....
I know it may appear I question Chris, but in reality, I am trying to understand what Chris has already determined and shares.
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They have thin air at 6,000 feet, which doesn't have much power in it.
The other extreme is somebody that lives on the plains at 1,500 feet elevation and you can see for 40 miles in every direction.
<RossBot> Density of 20.0 deg C dry air at 0 feet (1013 hpa) is 1.204 Kg/m^3
<RossBot> Density of 20.0 deg C dry air at 1500 feet (956 hpa) is 1.137 Kg/m^3
<RossBot> Density of 20.0 deg C dry air at 6000 feet (786 hpa) is 0.935 Kg/m^3
Applying those densities to the same turbine (17' DIA) in the same 30 mph wind, with the same generator efficiency (80%) and same coefficient of performance (0.2) sees:
30621.2 watts possible (4899.4 watts output)
28917.2 watts possible (4626.7 watts output)
23779.7 watts possible (3804.8 watts output)
That doesn't make any allowance for turbulence etc.
So...
RossBot, does that mean about 25% less power for them as one would see at sea level on a 20c day?
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Dan lives nearer to 8,000 feet than 6,000.
Thin air.
Tom
PS. Anotherpower seems kind of sluggish tonight?
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So...
RossBot, does that mean about 25% less power for them as one would see at sea level on a 20c day?
Yes.
And thanks Tom - updating the above:
<RossBot> Density of 20.0 deg C dry air at 8000 feet (711 hpa) is 0.845 Kg/m^3
21490.8 watts possible (3438.5 watts output)
So just air density alone, we go from just shy of 5kW to just shy of 3.5kW output from the same machine....
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A turbine designed for low altitude (pronounced "one of yours") would not perform as well as those designed for higher altitude (similarly, "one of theirs")?
The venerable RossBot already answered this with great precision. The answer is "absolutely". Take one of my turbines out to the Dan's site and throw it up and it'll sit there idling on the tower in a 30 mph breeze wondering when the wind is going to pick up.
At high elevation you need to swing a little more meat to get power.
This is where geared turbines really shine. Plant my 3.2 meter at 8,000 feet and all you have to do is swap out the 10 foot rotor for a 13 and throw some taller gears in 'er. :)
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Chris
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A turbine designed for low altitude (pronounced "one of yours") would not perform as well as those designed for higher altitude (similarly, "one of theirs")?
The venerable RossBot already answered this with great precision. The answer is "absolutely". Take one of my turbines out to the Dan's site and throw it up and it'll sit there idling on the tower in a 30 mph breeze wondering when the wind is going to pick up.
At high elevation you need to swing a little more meat to get power.
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Chris
It would be awesome for someone who has a properly built " not plans " from the Dans Homebrew 17'er to chime-in giving data from sea level and good winds.
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I guess that'd be me, basically the 17' Dans machine is mediocre at best, my site is a fair wind site but for the size of the swept area it is an under performer and really only shines in a vary narrow wind speed range, from 20 mph to 25 mph where it starts to furl, that's why I have a geared machine on the build stand right now, I'm tired of seeing Chris's little pinwheels making my 17' machine look like the toy in the group, in this case size don't matter.
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I guess that'd be me, basically the 17' Dans machine is mediocre at best, my site is a fair wind site but for the size of the swept area it is an under performer and really only shines in a vary narrow wind speed range, from 20 mph to 25 mph where it starts to furl, that's why I have a geared machine on the build stand right now, I'm tired of seeing Chris's little pinwheels making my 17' machine look like the toy in the group, in this case size don't matter.
Do you mind sharing some of the performance(less) statistics for your machine with us? Are you direct connected to your battery group? What battery voltage do you have? You are just who I've been looking for for details. Thanks for sharing what you can.