Troubleshooting Dual Rotor

[Shadow]

 After this big crash,

I built a new set of blades, First a little history, Its a dual rotor 12 mags, 9 coils of #17 140 turns, Old set of blades I hit 48 volts at 152 rpm. Today strong wind gusting up to 30 miles an hour. I cant get 40 volts , at any speed! Any two phases show 20-23 volts AC and all combinations about the same. But DC, the highest I got after adding about .04 resistance open circuit was 42 volts. Any ideas as to why?..Are my new blades that inefficient?They start up very easy, turbine stops instantly when shorted out,with the old blades I saw 135 volts open circuit, (before I knew better to do that). This just wont continue to build up speed. It definately over speeded lots befor the crash could this have damaged the rectifiers? My airgap may need a little adjustment but not that much. Any Ideas?

[Shadow]

Heres the new blades, I can never add more than one picture at a time here for some reason.

[Shadow]

These new blades have a slight ;sept back' appearance for some reason, all three about the same. The tracking is dead on.

[Shadow]

You can see by the trees how windy it is, lots of turbulance, but earlier was directly into good wind.

[harrie]

Wow Shadow, what the heck, didnt you have the stand ancored to the ground? I think your going thru a learning process like the rest of us. Ha. Anyway, If your using the little Square bridge rectifiers, it is possible that one of them may be shot. I burned out a couple the other day, when I had gusts up to 40 miles per hour. what happens when they go bad, it acts like a short, and will effectively slow the genie. I check mine by using my ohm meter and holding one lead on the AC termial that is to the left of the positive terminal, and than check across to the other terminals. You should only get a reading on the Negative terminal. If you read anything on any of the other terminals, it is no good. I have now placed three rectifiers on each Ac lead for a total of nine 35 amp rectifiers in parallel. Mine is also a duel rotor 9 & 12, 34 turns of double #14, with 12 foot dia props. It was puting out 90 amps DC. when the rectifiers quit. They were well heat sinked at the time also.

Have fun, harrie

[Shadow]

 Thanks Harry, I'll try that right away. No the stand wasnt anchored properly, but was never a problem. That blue strap you see fell off in the high wind and turbine spun out of control until it was like a sheet of plywood in the wind, then toppled over. All I would have needed was a plug-in shorted out to keep it from turning, tied or not. So now I keep it tied and shorted when not in use. I also anchored the stand.

[nanotech]

Something I saw on the way to work that might help you (now)...

There's one of the old-style well-pump windmills (ok, quite a few of them) on the path I take to work.  There's one that looks in fairly good condition that I never see turning, no matter how strong the wind is.  I began to wonder why until I saw that the tail was tied to the side, effectively furling the blades completely out of the wind.

Might be just another thing that could triple up the safety measures you use....

[Shadow]

Ok, mine are wired like this,

so you say test the two across the back ac in to negative? with my meter set on ohms(buzzing)? And are we talking with the turbine stopped or running?

[harrie]

Yes, that should work, however I found that three was not enough. I had six when two burned out. When you test them, have the wires disconected. There may be another way to check them, but I found that the ones I had that were shot, I could get a reading on my ohm meter across all the terminals. which would be a dead short.

Have fun, harrie

[harrie]

Oh ya, I forgot to mention that if it is one of the retifiers, it will act like you are running on two phase, and you should hear some viberation noise.

[jimjjnn]

It sounds like the bridges ( 1  2  or 3 may have shorted with the high winds that you had. What kind of current was it producing at that time? What were the bridge rectifiers rated at for voltage and current? I suspect that one or more are shorted keeping your mill from producing its former volts and current. Shorted diode acts just like a short across the phase.

Test your rectifiers unplugged from the mill otherwise your coils will show on your meter. Short out your mill at same time so you can't get hurt.

[Flux]

Shadow

You can eliminate the diodes if you disconnect them completely and run the generator in a light wind with your meter on the ac leads. It should pick up speed quickly and if you get to 40v ac easily all is well. Be prepared to short the leads and stop it

at about 50v. You have proved it by then.

The only sure way to test the rectifiers is to remove all the leads. There are 4 diodes in each package and your meter should show a diode between any adjacent pair of tags ( conduct with leads one way and not the other). Any pair that conduct both ways have a shorted diode, if you get no conduction you have an open diode, but that would not cause your present problem.

Flux

[DanB]

I think for 48 Volts 3 is plenty... if he's using 35 amp rectifiers or so it should be good for 2KW which isnt likely from a 10' machine.

I expect you might have lower voltage.

[Shadow]

I checked the rectifiers, all checked out ok. I had new ones to compare too. I climbed up and took AC readings off the stator, by giving the prop a good hard spin I got just a mixed up variety of voltage would jump from 12 -8-6-1-0.6-4-? any two phases I tried did the same. And no matter how fast I spun best I did for an instant was maybe 14 then immediatly scattered around again.Yet when you short any two out it stops quickly.I think time to build new stator? I had it off and examined it for cracks or damage but couldnt find a mark on it.but must have overheated?..or magnets overheated?

[Flux]

I wouldn't be inclined to build another stator at this stage, they really take a lot of hammering to burn them out. If there is no resistance to turning with nothing connected and shorting each phase will stop it I would think the stator is ok. It's a bit difficult to do much tests in the air but if you have the stator off, can you test the alternator at ground level by hand turning it without the prop, then you can see what is happening.

If you can hand crank it you should feel any sign of resistance due to a faulty coil, this may not be obvious with the prop on. All three ac readings should be the same and from your previous cut in figures you ought to be able to crank it to over 40v. With the rectifiers on, the dc voltage should be 50% higher than the ac for the same speed. If there are wild differences try another meter. With hand cranking each phase should light a 24v headlamp bulb fairly brightly.

If you had a crash, check for mechanical troubles that may cause stiffness such as altered pre load on the bearings or a seriously altered rotor to stator clearance, I bet it's something silly, not a stator fault.

Flux

[Flux]

Shadow

Just a silly thought, you haven't altered the placement of the 2 rotors have you?

With 4 studs I think it is a case of ok or virtual cancellation but if it has 5 studs there may be positions where it works to a point but you will only have the magnets directly opposite with one position.

Flux

[Shadow]

I took the prop off,and spun by hand. What I found was I have a plug connection at the base of the stand and apparently that was the problem, wires were shorting out in that connection, but just at certain times.(Go figure). Which made me shake my head at myself as it was not plugged in at the time it overspeeded so couldnt have possibly damaged any rectifiers! So now by spinning by hand I'm back to getting 48 volts at 148-152 rpm.But havent had a breath of wind since getting things back together. So Thanks everyone for the ideas of things to check!

[picmacmillan]

shadow, i came across a nifty little item the other day, and i used it to anchor my genny down...it is of course temporary, but i dont see any movement in the guy wires or anything...what i bought was, 4 of those spiral stakes yuou would use to turn into the ground and tie a dog up with...these things are very strong..you need a wrench to turn it into the ground all the way and it wont pull out..this saves from cementing the guy wires in...they also use larger ones for the telephone poles they guy wire....go give it a try, or anyone else who doesnt have the money or the time to cement the guy wires down...they are very inexpensive($5) each, and they work fantastic...finally, it is a shame to lose those blades, i always said, they were painted up beautifully.....you're mill looks fantastic, and i hope you get it sorted out..pickster