Author Topic: Iron Genny updates  (Read 7689 times)

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Offline philb

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Iron Genny updates
« on: January 15, 2012, 08:34:57 pm »
This story was originally posted in 2007.

I put updates and lessons learned in 2012 in bold.

It has some old and new ideas incorporated into Iron Genny's unique design.

Stats:
Double 12" rotors with 24 Neo magnets on each, 18 coils on each side of magnet steel laminated stator. I started out with an 8 foot diameter prop. Within a year, I had made a new 12 footer replacement.



Shorting out the stator was impossible even with the 8 foot diameter blades. Goes 222 blades did not know what stop meant. It's a helpless feeling knowing there was no way to shut this monster down! 850 RPM is as fast as both sets of blades would run, so I accepted it for then. :(

This unit was built in an attempt to accomplish several things:

   1. have fun! (I did have that)

   2. user adjustable furl (worked fairly well, but not good enough to duplicate)

   3. deal with excessive heat in the stator with a magnet steel laminated steel core
      (I had no problems with this)

    4. I wanted 24 and 48 volt capabilities. Yep, it would do >120 volts wide open.
      I let the magic blue smoke out of  two Xantrex chargers. Hmmm...Mppt candidate?


     5. Learn to seal the blades to keep moisture from entering and unbalancing them.
       Smooth-on 300 worked very well to seal and protect the blades.

     6. Build with a removable generator so changes could be made inside the barn.
     
     7. Easy to replace tail bearings and ones that would not come loose from banging the stop.

Stator construction:

I started off with a piece of 3/4" silicon magnet steel about the thickness of steel banding material and yards long. It was wound just like the stators were made on the old, old Otherpower board. I used the same mold I had made to cast the rotor for winding the laminations. The laminates were wound as tight as I could get them.

Next, it was drenched in electrical varnish. It was allowed to air dry and I used a propane torch to dry it further. I bought it in a gallon can from the same place as I purchased the magnet wire. This stuff was nauseous, but worked like extra starch in a shirt!

I quickly learned the magnets would still warp the laminates. So, I drilled 18 holes around the parameter and inserted 1/4" stainless steel all-thread.

Two 3/32" thick steel hoops were added to secure the laminated steel firmly. The inner hoop is black and the outer is rusty. I also had to weld the laminates about 1/8" deep on each side using a 308 stainless steel rod. The varnishing process had to be repeated. ( This is part of the learning curve.) The 1/4" all-thread was tightened evenly around the hoop with a torque wrench at 12 ft/lbs. Welding the laminates were a mistake, I think. At the time, there was no other way to keep the laminates from warping under the pull of the neo magnets. I would attempt a Proven type stator today.



The coils came next.


The laminates were covered in painter's tape to avoid any sharp edges coming in contact with the magnet wire. 30 winds each, #18 magnet wire, 18 coils on each side. The legs of each stator were taped together, then the stators were tied with string to keep them on the laminates and in the right place. Varnish was sprayed on the coils, string and connections. Krylon varnish is much better that the dip stuff I used earlier, BTW.

Smooth-on 300 plastic was brushed on both stators to seal and 'glue' the coils on the lams. Both stators were wired separately in star and connected in parallel. 12 wires come out of the completed unit and are tied together at the terminal block on top of the tower. I did this to change configurations from star to delta easily. Just in case I needed more options. The box that houses the terminal block can be seen in the first picture, just behind the stator. Each stator produces about 30 volts when spun by hand. In the near future,

I used a 12 diameter piece of 1/2 steel for the rotors and mounted 24 magnets on each one. Magnets are the 3/32 thick neos from Windstuff Ed.
The edges of the magnets do touch the edge of the rotor. That small distance created  'stops' to keep the magnets from sliding off.  I cast the entire rotors in Smooth-on 300 and painted them. There's still no rust on them even though it's been on the ground since last May.

I think the magnets will cause some power loss. All of this has it's trade-offs.


The 8 foot diameter blades were from my one of my earlier generators. Water was entering the wood where the blades were bolted to the rotor and causing balance issues. I drilled out the holes by an inch, poured the Smooth-on into the holes and redrilled them to ½" bolt size. Maybe this will work. It did well.

Today I would have used steel bushings. 12 foot diameter blades were made later after the smaller blades were damaged by a loose guy wire.

Here's the adjustable furl mechanism.


I attempted make two hinges from the compound hinge assembly, commonly found on Hugh and DanB's machines. The first one that's attached to the yaw bearing pipe is welded in at 10 degrees up from horizontal. The second angle is adjustable to whatever you want. It's a pipe within a pipe, secured by tightening 4 top bolts. If the bolts fail, the tail should drop and cause the genny to turn out of the wind and slow down. Out of balance blades should also cause tail drop. Can you say run backwards Niall? :) Oops, that was an earlier one. :) Surprisingly enough, this mechanism was very touchy. I learned from this experiment how critical the furling angles actually are. When you get them right, nail them, weld them, whatever it takes.

I used DanB's method using of using rope and a fish scale to adjust the furling. It's set at 10 pounds.  This got me in the ball park, but that's about it. Hours were spent getting this set after it was on the tower.

The generator bolts to the flange on the left.Notice the bearing on top of the yaw post? It worked well. That's a keeper. Very responsive to variable winds.

Here's a mach-up of unfinished generator.


I've seen 60 volts going into the batteries and 70 Hz when configured for a 48 volts system. The Hz are high enough, it may get a transformer hooked to it, just for fun. No need. As yet,I don't have good solid data on it's output. I plan to hook up my datalogger to it soon! Never got around to this in 4 plus years.

I had the iron genny hooked to a fully charged 48 volt battery bank being controlled by two Trace C-40's. It didn't take long to determine when the C-40 is bypassing power to the dump load at 9.3k Hz, which caused the values on the meters to change rapidly. I question now if my meters were accurately reading RPM and Hz at that frequency. I still could not use all the power the generator was making. I ended up with 4 overcharged and bulging T-105 dead batteries.

Next, I hooked up a scope to the genny. At about 70 Hz or less, I got a pretty good sine wave.


Higher Hz chopped the top and made it look more like a PWM trace.
This picture shows 124 volts AC before the diodes @ 181.4 Hz. The diode chop is visible.


Here's a picture of the dump load. Nichrome wire on a ceramic board. I think it needs to be resized with more resistance.

The battery voltage was still higher than 48 volts after 2 hours. Those 222 blades do pull hard! They remind me of the way diesel engines pull under load.

Below is a picture of my new and soon to be returned multimeter. It's supposed to do AC & DC watts, volts, amps, everything but ohms. Most of the time, it does what IT wants. I only got a few good watt readings. The wattage on this genny ranged from 0.5 kW @ 60 Hz to about 3.3 kW @ 104 Hz.
Expensive toy. Here, it is registering the AC dump load (above) at 1.69 kilowatts correctly. This was an experiment to see if and how much I could slow the RPMs down. As I remember, the dump load took about 25 RPM off the top.


Notice the copper bar behind the meter? It was put there for 12 and 24 volt systems. It would be really hard not to bay at the moon if I were to touch it now. I should have planned for the higher voltage generator better.


TTFN,

Phil

Offline niall

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Re: Iron Genny updates
« Reply #1 on: January 16, 2012, 04:05:57 pm »
nice to see the updates on that mill Phil...looks like you were well on the way to a Proven type alt  design there ...(with the other downwind event )...  :o...the provens seem a very strange fish

backwards ...or is it forewards ...or are all upwind machines actually backwards and they dont know it ...lots of fun .. :)

Offline oztules

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Re: Iron Genny updates
« Reply #2 on: January 16, 2012, 07:25:39 pm »
Thanks for reworking the story..... I like to see hind sight and better ways to do things after the event...... I don't feel so lonely

It certainly is different, and as Niall commented, your not that far from doing a torroid.... something I would like to experiment with.

Impressive figures for such small magnets.



.................oztules
Flinders Island...... Australia

Offline philb

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Re: Iron Genny updates
« Reply #3 on: January 16, 2012, 08:40:33 pm »
nice to see the updates on that mill Phil...looks like you were well on the way to a Proven type alt  design there ...(with the other downwind event )...  :o...the provens seem a very strange fish

backwards ...or is it forewards ...or are all upwind machines actually backwards and they dont know it ...lots of fun .. :)
You hit the nail on the head niall! Objective number one - have fun!

Oztules- I thought about doing a toroid on this one. I couldn't get my fingers around the iron. I know how to do it now. I still have about 80 lbs of the 3/4" silicon steel and 50 2"x2"x0.5" magnets saved for a special occasion. :)
I suspected the voltage would be high, but not as high as it turned out. I took each phase out of the stator independently. They were tied to a terminal block outside. I was able to use several configurations easily enough. I wanted all the options I could get. 

It either needs better furling, a brake or variable pitch prop to control it though.

I'm glad you enjoyed the post and
Thanks for the responses.
Phil