Author Topic: Finally fried (Read 3374 times)

Hank · « **on:** May 29, 2009, 03:58:08 PM »

After 5 years of trouble free service (for the most part) it fried.

Don't know when or how as it happened over winter when we were not there and it was shorted out during that time. The stator is totally cooked, lost one magnet, prop has some damage but fixable.

Haven't been on the board for a long time and as I'm going to rebuild I thought I'd share this and also get ready to ask questions (this forgettery thing Alzh.. something or other)

Hank

Oversized image given one-time tweak, see Frequently Asked Questions. Looking forward to details and solutions as you discover them! DanG

SparWeb · « **Reply #1 on:** May 29, 2009, 12:17:24 PM »

Wow

I can't see scuffing on the stator, on this side, at least. If there isn't any on the other side, then maybe it's more likely a one-time event than a long-time misalignment or deformation. About all I can say.

I hope you can have a replacment back in the air soon.

electronbaby · « **Reply #2 on:** May 29, 2009, 12:38:13 PM »

Prop looks like it is mounted with quite a bit of offset from the hub. Is there any play in the bearings? It could have flexed possibly and rubbed the stator???

I think it would have to be spinning to do this. Is there any rectifier damage?

I also am interested in what you find.

Please keep us posted.

Hank · « **Reply #3 on:** May 29, 2009, 12:48:55 PM »

I'm not sure what happened, all that I can say is that last summer I put on another prop and at that time I also noted a bit of rubbing so I realigned the stator. At that time it showed signs of bulging and over heating, non-the less I used it some more especially during hunting season with no problems.

Last month when we went up to our camp we noticed all the wires hanging out so down it came. It was a mess, the stator and coils looked like they were very much over heated. Perhaps we did not short it out as we thought and with some high winds over the winter it fried.

I've already started to rebuild and am almost finished. Fortunately I had a replacement magnet and a stator. The prop just needed some Bondo touch-up and all will be ready to go soon.

Just have to do some recalculations to balance the unit as the new stator is of a different configuration then the old one (fewer windings w/thicker wire)

All the best,

Hank

Hank · « **Reply #4 on:** May 29, 2009, 12:59:07 PM »

The off-set it just the thickness of one nut which holds the hub down. Bearing has no play nor is there any flexing of the prop. I still have to check out all the electrical components, rectifiers, wires etc.

We had a severe ice storm here in New England last December with extensive damage to trees. Though quite a few trees were down near the wind mill it did not sustain any damage. I still have to check my wire run from the wind mill to the control center to make sure no fallen trees broke these lines. This weekend I'll check all that out.

Hank

turby44 · « **Reply #5 on:** May 29, 2009, 02:32:29 PM »

wow,,that looks like its had a rough time,it looks like a lightening strike,wires dont necessary have to be burnt out but look for scorch marks at the base of the tower where it swivels,lightening can behave in very strange ways but there is usually some other evidence.

good luck with your rebuild.

turby.

ghurd · « **Reply #6 on:** May 29, 2009, 03:01:48 PM »

I can't see scuffing on either side, so maybe it'll be OK?

Might be the first photo to show both sides of a stator at the same time.

Sorry about your machine Hank. Trying to lighten the mood.

Off-set from the tower to the hub axle?

Glad it will be flying again soon.

G-

Hank · « **Reply #7 on:** May 29, 2009, 03:08:01 PM »

Perhaps you are right!

The prop was not all that damaged, mostly just one blade had some dings in it from the stator wire. If it were a runaway situation I would expect much more damage. Also the magnets did not show signs of excessive rubbing as I would have expected in a runaway situation.

One thing I am noticing now that I have a new stator assembled on it is that my expected output is much less then based on the original design. It would appear that my magnets have lost some flux.

Unfortunately I don't have a gauss meter to measure them.

The stator that fried had 9 coils of AWG 16 wire with 80 turns/coil. It's rpm/volt was about 6 in star configuration. Now I have a stator with 9 coils, AWG 14 wire w/50 turns per coil.

I would have expected an output proportionally less in terms of rpm/volt (or higher rpm/volt)but this one is almost 3 times higher rpm/volt at 16.

Go figure! I guess it'll work fine for my needs I just may have to rethink the prop size and configuration.

Never easy is it?

Hank

Flux · « **Reply #8 on:** May 29, 2009, 03:15:35 PM »

You say you had it shorted but it started against the short in a high wind. This is always a worry. If a short holds it in most winds you get confident that it will never break away but in this case it did. Once it pulls out of stall it is certain death into a short circuit.

You basically said it was burnt out before, many of these things run more or less burnt out for a long time, most are pushed well beyond normal working temperatures and the life is likely to be short. If you didn't have all phases shorted together then that would have made the chances of it getting away from stall much higher.

There are always dangers associated with short circuit braking. In many cases things survive better if left running if they furl properly. For something that is left unattended some back up way of stopping it makes a lot of sense. If not the alternator must be very large in relation to the blades. In this case it will perform badly without some resistance in the line. This resistance must not be included in the braking circuit. I have often suggested using smaller line cable to improve performance. this is fine with things running and furling but the extra resistance goes against you if you try to hold it braked.

Flux

hiker · « **Reply #9 on:** May 29, 2009, 03:34:57 PM »

what a mess.......

might try tyin off the prop next time you leave for a long spell......

Hank · « **Reply #10 on:** May 29, 2009, 03:39:43 PM »

Hi Flux,

It's been a long time.

All is speculation as I don't know the cause of failure. When I short it out it's always all phases and it served me well even in winds approaching hurricane force. As I posted earlier I don't think this was a runaway as the damage to the prop was minimal (perhaps lucky) but the stator was totally shattered with wire wrapped around everything.

I have been fighting this furling trial and error thing for some time. On my last servicing of this PMA I lightened up the tail quite a bit to have it furl earlier, which it did.

I'll do some more investigation when I get out to the land this weekend.

I don't know what the life expectancy of these units are but 5 years is not to bad (that's the optimist in me).

Hank

kurt · « **Reply #11 on:** May 29, 2009, 04:41:05 PM »

Hank, dang gave you your one warning about the oversize pictures from now one everything you post with an oversize photo in it just disappears the rules are less than 150 KB file size and less than 640 x 480 pixels. thank you....

Hank · « **Reply #12 on:** May 29, 2009, 04:45:10 PM »

Oops! Sorry Kurt won't do it again. It's been a long time since I've posted on this board and forgot the rules.

My fault, I apologize.

Hank

tecker · « **Reply #13 on:** May 29, 2009, 05:02:13 PM »

It's clear you got good service from your build I assume this was your first .The mech is still good to go maybe some T braces to the stator bracket . A mag and coil on the back of your magnet rotor works well for a brake where the output of the stator is switched through a large coil that adds more hold should the stator brake away while shorted . Large coil with awg 12 that goes in series with the three phase .One coil for each phase wound together for a three phase coil.

tecker · « **Reply #14 on:** May 29, 2009, 05:05:41 PM »

Trifillar

ghurd · « **Reply #15 on:** May 29, 2009, 05:27:44 PM »

Big Pics go away, but I saw it.

Wondering about the lightning thing, and how the black is uneven and gooky looking (not paint?).

G-

TomW · « **Reply #16 on:** May 29, 2009, 06:36:14 PM »

Hank;

That thing looks like it exploded!

Heres a link to the large version of the photo:

http://www.otherpower.com/images/scimages/48/Fried_1.jpg

For those who like to see the details.

Tom

Hank · « **Reply #17 on:** May 29, 2009, 06:53:39 PM »

Thanks Tom,

I just forgot about bandwidth and all that good stuff. Didn't even look at the size of my pic's before I posted and also didn't see/read kurts warning.

Just getting old I guess and the eyes are failing. Cataract surgery next month.

How are you holding out?

Hank

TomW · « **Reply #18 on:** May 29, 2009, 07:34:07 PM »

Hank;

Doing OK, had a cluster of heart attacks about 4 years ago but seem pretty good to go. Usual aches n pains from a life lived like I did. Bucked up, split and hauled in about 5 cords of firewood in the last week or so. We ran mighty close to out this past year as I had not really worked up any wood since the health stuff caved in on me. Luckily we had just stuffed the woodshed with 10 or 11 cords of wood just before that little episode!

Got a 6.5 foot Zubbly Built [R.I.P.] turbine at 60 feet, a 10 foot original DanB Volvo type 10 footer with an 8 foot prop on it flying at 30 feet. We recently added solar to bring us up to 850 watts plus a new 600 AH 24 volt battery bank. So the RE is rolling along slow but sure. Hope to get a new 10 foot Otherpower turbine kit put together and up on a 50 foot 6.75" pipe tower this summer.

Some pictures mostly big ones for detail are over here:

http://pics.ww.com/main.php?g2_controller=useralbum.UserAlbum&g2_navId=xef9be877

Hope the eye surgery does the trick for you.

Tom

Flux · « **Reply #19 on:** May 30, 2009, 12:59:44 AM »

I don't think there would be any run away with it shorted out. The thing would cook at quite a low speed, not much above a fast crawl and weaken the resin to the point that the torque would shred the whole thing when it became brittle.

If it was already well cooked and brittle it may have been well on the way and the heat from previous overload may have weakened the magnets to the point where it didn't have the original braking torque. Neos don't have much in hand heat wise and with a heavy stator current producing a demagnetising field and the heat from an overloaded stator they may have weakened.

Flux

Airstream · « **Reply #20 on:** May 30, 2009, 08:40:17 AM »

With five years age I am guessing the stator casting was 'Bondo' polyester resin & the ice storm could've set up some inconvenient movement and ice welded some strands to the rotor (repeatedly?) to get pulled when the blades shed their ice.

When the 3-Phase was shorted, was it at tower base or end-of-line, and what are the tower drop line and transmission line sizes, & where were the wires bridged, before or after the rectifiers? Flux already noted where resistance works against safekeeping via shorting.

Its now the weekend, hopefully Hanks ring-out of circuits will have a tale to tell...

oldculett · « **Reply #21 on:** May 31, 2009, 08:14:30 AM »

your link does not work.

TomW · « **Reply #22 on:** May 31, 2009, 08:31:34 AM »

Old;

Try this one:

http://pics.ww.com/v/TomW

That was copied when I was logged in so maybe doesn't work for others.

Sorry.

Tom

ghurd · « **Reply #23 on:** May 31, 2009, 09:00:19 AM »

(The 1st one goes to the same error I get after logging in)

G-

Hank · « **Reply #24 on:** May 31, 2009, 03:47:12 PM »

Some nice pics there Tom,

Sorry to hear about your ticker problems but from the sounds of it you're well on the road to recovery. Stay healthy will you.

Went out to the land and apart from planting the garden I did some more investigatory work.

What I found is that one of my diodes was fried (have resistance measured both ways) This diode only handled one of the phases. The other diode was fine.

There are no open circuits in my feed lines from the PMA to the control panel so the unit was shorted out during the winter when not in use.

Everything else in my control panel is working fine as I also have solar panels and a Chinese diesel DIY back-up generator tied in as well.

I'm basically ready to raise it up again just have to determine my prop size as this will be a weaker PMA due to flux loss in my magnets.

The rest of the story will never be known as I suspect gremlins were at play or perhaps vandals. Last year someone stole 6 of my batteries. Fortunately they were at the end of their lives and not part of my charging/power system.

Having fun though,

Hank

News:

Author Topic: Finally fried (Read 3374 times)