geared wind turbine or direct drive

[Bio Diesel Man]

I have been reading and talking in the past about Chris Olsons turbines..Chris has a good looking and operating machine it seems,,but now I see he is building a direct drive turbine with neo. magnets..I   too am ,slowly putting together a geared wind turbine with C8 ceramic magnets,, like Chris was building,,but was just wondering if he has had a change of heart on the geared units..Are there problems with the drive chain and gears wearing out or is there other issues going on with the geared units that would make us maybe want to think about going back to Hugh"s design of a direct drive ceramic magnet unit?? Hope someone can answer these questions,as I have the frame all built the rotors all trued up and am ready to weld the claws on each rotor to help hold the magnets in place after they are JB Welded on..Next step is to make the stator mold and try to figure out the coil sizes..   Thanks, for the information you all provide to us.. Duff Streeter   Bio Diesel Man

[ChrisOlson]

I designed, built, tested and posted that build on my website for homebuilders who want a purpose-built turbine specifically for the Classic 150 MPPT controller, and that will work on any voltage system with no modifications to the turbine or stator.

The direct drive is MUCH easier to build than a geared turbine for homebuilders, and there are no other "plans" that I am aware of for a high voltage MPPT turbine for homebuilders.  You can strap a Classic 150 to an Otherpower 10 footer and maybe get 1500-2000 watts from it.  It takes a special-built one, designed to run at 150 volts, to get 3 kw from that size rotor.

And that's the purpose of the build - to show folks how to do it.  It is not a cheap turbine to build, however, with the cost of the controller and 40 magnets.  But it does perform very well.
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Chris

[Bio Diesel Man]

Hey Chris,   Thanks for your quick reply...   I was hoping you would set me straight on the questions I was asking.. I will keep pluging along on my turbine and hope someday to get it done..   Thanks Bio Diesel Man

[tecker]

I have several rearends from early  model tucks small and mid sized I think that they made be a good build.

[Harold in CR]

 I have a spiral/bevel gearbox that I bought new off ebay, for $40.00. It's round, cast iron case, and a hollow shaft. It's 10:1 gearing. Perfect for an 1800 RPM alternator. I used one for the 4KW turbine I built, back in '79. Had the blades on a feathering hub, ala Jacobs design, and it worked well until the tornado threw the blades into the brush, about 9 years after I got it up.

 Never had to add trans fluid, which I thought was the best, low viscosity, heavy duty oil I could find.

 I'm going to use this one for a Permanent magnet alternator setup, IF I ever get the time and money to build the 80' tower for it, or, get tired of the trees and cut and saw them and sell them for the tower money.   

 

[Frank S]

several years ago while visiting a  country in S Africa I saw a few turbines that had old small truck transmissions mounted between the turbine blades and the generators.
 I remember 1 that looked like it had a 7 or 8 ft water pumper fan mounted to the output flange and 4 belt driven car or small truck Alts connected to pulleys on the input shaft

[fabricator]

IMHO 10:1 is gonna be too much, my 4:1 takes a LOT of torque to turn that alternator, you would have to do some serious figuring to make a machine that would not be stalled all the time or, plan on using a classic right from the git go.

[ChrisOlson]

The bigger the turbine, the higher the gear ratio you can use.  You're trading torque for speed in the gearbox, with about 6% loss in a chaincase type transmission.  You'll get higher losses with a gear drive that uses pre-loaded tapered roller bearing sets on the shafts.  My chaincase transmissions are designed for low drivetrain losses by using ball bearings and an oil bath roller chain, which develops less friction and heat (and hence lower losses) than gear to gear.

Small rotors don't develop much torque, so you have little torque to trade for speed.  Larger rotors develop more torque, so you can use a higher ratio and trade that torque for speed to keep the generator smaller and more economical to build.

Blade selection is also important.  The high torque GOE222 has proven to be the best with a geared drive.  With a Classic you can use about any blade you want and use the gearing to get the voltage up to 150.  The direct drive I recently designed has a very expensive generator on it compared to my geared turbines.  The direct drive generator costs 10x more to build than the high voltage ferrite generators on my geared turbines that produce similar power levels with a 3.5 meter rotor.

The direct drive generator is also quite noisy compared to the geared generators because it runs at lower current frequency and the harmonics and coil vibration is more pronounced in it.

While the geared turbines have several advantages, they are not easy to build because you have to pay attention to shaft alignment and chain tracking.  While a roller chain will handle some misalignment, if the chain doesn't track properly due to misalignment of the shafts, it will wear the side the smaller pinion unless the pinion is running in the oil.  On my larger geared non-MPPT turbines I put the pinion at the bottom to keep it in the oil.  On the later MPPT turbines I put the pinion at the top to reduce viscous drag- and then you have to pay closer attention to shaft alignment.

On the geared MPPT transmissions I align bore the transmission case on the vertical mill, with the shaft centers precisely set for proper backlash in the drive, and the bore in the case the proper size so the pressed flanges "seat" in the bore to insure perfect shaft alignment when the transmission is assembled.  Not an easy thing to do for the average homebuilder unless he/she has a complete machine shop.
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Chris

[Harold in CR]

 

10:1 is gonna be too much

 I bought a GE 1800 RPM 4 KW alternator from Surplus Center.  I found an engineer in Tulsa that did all the figuring for me, and, he concluded that a 16' blade span would put out sufficient HP to spin that alternator at 1800-2000 RPM's and that is what I set the governor speed to, roughly 220 RPM's max. I tuned it by watching the wind speed on the anemometer, and, climbing the tower and adjusting the springs on the governor. I would drop down some, and my son would call out the amps as I ducked under the blades.

 Only real problem, was, getting the turbine to fold up under a 20 MPH wind, so I could adjust while not having to climb up and down so much.

 I saw the machine put out 20A on each 120V line, max. I ran #4 welding cable down the 80' tower, and another 70 feet into the battery shed.

 I had 1-120V leg hooked to a Lister 36V output golf car battery charger to 1 part of the battery bank. I had the other 120V leg hooked to a variac, and, on slower wind days, under 20 MPH, I could up the V output on the variac to get 10A + through a 30 Amp ammeter. The Lister charger would just put out a variable Amps, as the wind would increase or decrease.

 I never went to college or had any machine training. Just used my head to figure (overbuild) stuff, and ask people that were trained to use them calculators.

 I was not into always getting maximum output at all speeds, just all the machine could do whenever the wind would blow. 

 NEVER saw the thing get stalled out ?

 I mounted the alternator inside a 12" well casing, cut out the front to allow bolting the gearbox directly on the casing, and sealing it up a little. Had a small field disc that I cut down for the back cover, and built a slip ring block for the leads to not twist up. Used GM starter brushes for the contacts on the slip rings.

 Built the tower with the guy I was helping put up wind turbines.

 Just sayin. 

 Below is a photo of the type Browning I used the first turbine I built.

[ChrisOlson]

While you can use bigger turbines on grid-tie systems OK, I feel there's a practical limit to the size of battery charging turbines.  The Bergey Excel-R is a good example; it has never been that popular with off-grid people because it's too big and too expensive.   For the $40,000 spent on a Excel-R you can install 20 kW of solar panels.

Smaller sized turbines take way less expensive towers, and the tower ends up being most of the cost of the wind turbine.  Plus you don't have the problem with excessive capacity on windy days, since most battery banks can only be charged at C/10 and there's a limit to how much "dump load" you can have that is useful only a few days out of the year.

Most people have the mistaken notion that they're going to power their home with a wind turbine.  In reality, the wind turbine is part of a total package for off-grid power that includes solar (and possibly hydro) along with a backup generator.  Solar and wind power tend to complement each other.  The wind power can work 24 hours a day, while the solar only works part of the day.  And one can work on one particular day when the other doesn't work.

You don't need a big turbine for that - when you live off-grid the bulk of your power will come from solar and the turbine's job is to fill in the gaps and provide extra power for water heating and to prevent having to run the generator.  In some areas the wind power will tend to be the dominating force in the winter, while solar will dominate in the summer.  Again, this does not take a big turbine - what it takes is one that produces 250 watts @ 12 mph, and if you need 500 watts @ 12 mph then put up two of them instead of one bigger one because the cost of the tower increases by 5x when you go from a 2.5 kW turbine to a 5 kW machine.
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Chris