It's been a few weeks since I posted about our activities...
Lots of stators got made and there are a couple in the mold now.
Scotty came up to build a new stator for his 'mini petter' diesel. the old one works still, but he wants more efficiency - wants to be able to run the engine more slowly and doesnt need the 120VAC coils that we put in the first one. This one has 8 coils, each wound with 3 strands of #15 gage wire and 35 turns each. Each coil will be separately rectified. My guess is it will work very well and be very efficient - he may need to open the airgap so it doesn't overpower the engine too badly.
Last couple days we've been having gusts around 90 mph (national weather service says up to 95). TomH left his wind turbine on and the tower failed yesterday in the morning. Actually - we had anchored his short 30' tower to a rock, with rebar that was epoxied into a hole in the rock. To that we welded a link of chain to fasten the guy wires. The chain link broke - the tower came down. It missed his solar panels by inches. The blades got turned into mulch.... the alternator/tail seem to be fine.
Like I said - the tower missed his panels by inches....
One of my last postings here was about the spotted owl hitting the blades on my 20' wind turbine - and I've never posted about that incident since. Actually (what really happened) - the blades deflected (probably on a very fast yaw in very high winds) over 16" and one struck the tower. We never really did run the machine for long with the 'duct tape' fix (about 1 hour just for fun) - but Scotty found most of the missing parts and repaired the blade. Pictured above is one of the repairs.
Another picture of the same blade after repairs.
Like I said - he found most of the pieces. Pictured above is another interesting splice. At any rate - the machine was down for about 1 week over that mishap. Now I'm more careful with it. Some of you recall that we had issues with it last March and decided to open the airgap slightly (to keep the magnets out of the stator). This caused the machine to really perform well I think ( a bit too well actually ). It runs a fair bit faster and makes lots more power in high winds. This season the record output has been 8.5 kW - it's very quick in higher winds to make a steady 5kw. With the origional airgap it was fairly hard pressed to produce over 3kW. Im inclined to raise the tower a bit and get more blade clearance (the blade struck a guy wire mount). I may also cut down the blades slightly - or.. close the airgap - or - install higher grade magnets to prevent this (or try). As it is now - its working well, but I am being careful on windy days/shutting it down often.
Don came up to build a wind turbine. He'd been given an old one we made (one of the first volvo strut things) and I told him hed be better off to knock the magnets off those rotors and use them in one of our newer designs. So he did... at this point hes got his stator done, magnet rotors cast and most of the metal work done.
Shawn (who came up /built a 17' turbine last year) is getting close. Pictured above George is helping Shawn built the top stub for his tower. We use 3" pipe for that... and the yaw bearing is made from 4" pipe. I've never found a really good fit between pipe sizes this large so we weld 1/4" thick (1" wide) bar stock to the pipe, heat it up to about yellow and hammer it so it fits tightly to the smaller pipe and makes an OK bushing for the yaw bearing.
TomW (different Tom W than most of you are used to but surprisingly similar in appearance) came up to build a 20' turbine identical to mine (his has higher grade magnets in it). He's got his magnet rotors and his stator done so far and a bit of a start on the metal work.
One of Toms magnet rotors with all the magnets cast. Notice the magnets are numbered (you have to look closely) - there are 20 magnets... 20 numbers.
People have spent hours so far (its been at least 3 weeks since the magnet rotors are done) playing 'bottle cap darts'. (its an approximately $600 dart board) It's really quite fun - the magnet rotor is numbered exactly like a dart board - you have to toss bottle caps at the magnets and call your shots. Just like darts... there is a minimum bet (1 nickel). Gobs of fun.... (patent pending)
Scotty's hydro plant quit working well - two phases died. It runs a very wide airgap but the stator was not centered (it was too close to the back rotor) and the bearing got loose. It wore well into a couple coils and cut through the wires on one. He actually managed to find the break in the wires and repair it with a splice!
I got to thinking about previous discussions here and the possibility of a galvanic reaction between Nickel plated magnets and steel rotors. If there is a reaction (which there is) the steel should really be the victim of most of the corrosion - but I wonder if the Nickel doesn't slowly corrode as well (dont know - I have never had a problem with magnets rusting yet). Pictured above is a .5 Volt battery... I expect it could be optimized to produce quite a bit more though. Each steel disk has a bit of rag soaked in a very weak saltwater solution and each such cell produced .2V. When I stacked them though I only got an average of .1 V per cell (my guess is the point at which I stacked them also acted like a battery - just lower voltage and reverse current. At any rate though - there is definitely some galvanic stuff going on between steel and Nickel, I don't know how much of an issue it might be in a humid climate.
Other news... My 17' turbine had an interesting failure... I've not been very attentive about unwinding the cord down the tower and it finally twisted up so tight that it shorted out/sheared off - and the line fell down the tower.
That's most of excitement in the last 3 weeks or so anyhow!
