16 footer fried stator update

[Hilltopgrange]

Hi Guys
           Well I guess I have made it over from the old board! but not without some problems. The biggest problem was me, I am a creature of habit that doesn't like change. Anyway I have been able to find my way around eventually though I do miss my hot list and find it a little difficult keeping track of stories. To be honest I very nearly gave up and even started looking for alternative forums to lurk? but I persevered with it and now find I am starting to enjoy it again.

Some of you might remember my last post about the crispy fried stator,

http://fieldlines.com/board/index.php?topic=138518.0

well the wind finally dropped enough to get the tower lowered and the alternator striped. What a mess! well and truly burnt to a crisp with every single coil well burnt and swollen to the point of rubbing the rotors,several have blown holes in the glass fibre. So that's that as they say, one new stator required. This one will be wound with 2 x 1.80 mm (previously 1.60mm) and I will also trim about 3 inches of each blade.

This machine (16ft)has failed to furl on a couple of occasions and there has been a lot of debate as to why, the general consensus was that tower location with regard to the house and hill was causing the failure. I think I have found the culprit, the the yaw tube was seized solid on the mast stub. The tower is a lattice type with a 10 foot stub fitted in the top section and this stub was welded to prevent movement within the tower. The welds were broken and the whole 10ft stub was yawing with the turbine. I have yet to remove the alternator from the stub but I think it is going to need a lot of heat and large sledge. Its amazing that this machine tracked the wind at all, it takes considerable force with a 4ft lever on a chain wrench to rotate the stub. On the plus side at least the cause has been found and its just a matter of fixing it.

The magnets and rotors etc are fine and just need some fresh paint, the magnets are screwed and glued to rotors and are not potted but had several coats of paint to weatherproof and this seems to have held up very well with no sign of rust on the magnets.

I had fitted several grease nipples for the yaw tube and bushing and pumped it full of grease but I think a few mods are required. I will machine the bushings to give a bit more slap and fit auto greasers to each bush. With this being a lattice tower I can climb it and grease it every couple of months and hopefully avoid a repeat performance.

I hope to get the tower sorted while I wait on the wire arriving.

There has been a strange yellow thing in the sky for the past couple of days it moves slowly form the east to west and the sky has been a funny blue colour! very strange and unusual, rumours are that it is the sun but I Think it is more likely to be a visiting ufo or slow moving comet.



I didn't get any pics of the stub or tower but here's a couple of the burnt and rather smelly stator not much to look at but at least I get to see if I can still post pics.

Russell

[bob golding]

that third pic looks like a corona eruption from that strange yellow thing in the blue sky. i would send it to patrick moore.

[Hilltopgrange]

The only corona you see round these parts are the cigars!

[Flux]

I am glad you found the source of the trouble, I wasn't entirely convinced about the site position but it was all I could suggest at the time.

That is a good example of a fast burn out that probably took place in seconds, it virtually explodes the coils as the stink and vapour forces it's way out. Slow overload normally gradually chars the wire coating and it will run in a part burnt out state for a long time until it eventually develops an inter turn short or it expands to the point where the magnets rub.

I suspect there are a lot of burnt out machines still running.

Thanks for the updates, I also  struggle with change and I find the new board strange but shall come to terms with it.

Flux

[Ungrounded Lightning Rod]

Yep.  It's really hard to get the furling working right when the yaw bushing has seized.  B-)

[Hilltopgrange]

Hi ULR
         Its good to find a definitive fault, makes fixing it a bit easier lol.
It was impossible to see this from the ground, I'm going to make a few changes to the bushing to reduce the surface area and improve lubrication.
There was six welds on the tower stub that broke allowing it to rotate,so I think I will bolt and weld it this time, and paint a stripe down the stub to show if it does it again. You think your doing the right thing with tight tolerance's when in fact the more slop in the fit the better.

Russell

[Hilltopgrange]

Hi Flux
         I cut one of the coils out today and it is completely burnt with virtually no enamel left. If you shake the stator the coils are all rattling around within the resin cast! a lot of the resin has just vaporised,. just shows how hot it got.

Thanks for your comments.
Russell

[Flux]

You didn't by any chance use that polyurethane enamel did you? It's normally a pink or red colour although it can be green.

That stuff totally disintegrates in a stink of something nasty and leaves virtually bare copper when badly overloaded.

Flux

[Hilltopgrange]

I'm not sure as I bought of ebay, it seemed a good deal at the time. When it eventually arrived it wasn't even on a spool, it resembled a birds nest in a box and took about 4 hours to untangle. It was brown in colour and as you say is now just plain copper and black dust.

I have managed to find a motor re-winder reasonably local so hopefully they will be able to supply my needs. Its very difficult to get winding wire this side of the Irish sea, there is only about 4 re-winders and so far 2 are unwilling to sell to the public, seems strange to turn away business but its their loss.

Regards Russell

[Hilltopgrange]

Hi all,
           just a quick update on the burnt out 16 footer, after much ado it is back up and working. I made a few changes and found a couple of problems which I think contributed to the failure.
I rewound the stator with 1.80mm wire two in hand originally it was 1.60mm x 2. I had a heck of a job winding the coils tight enough to fit but eventually I managed it.
I mentioned in an earlier post that the yaw tube had seized to the tower stub this I cured with a grinder by creating a bit of slop on the side thrust bushing. I reduced its size and ground grooves to reduce its surface contact area. I have also ordered automatic greasers to insure it never runs dry. Hopefully this will help.

I built the alternator and re-fitted the blades, tracked and checked the balance I then discovered a silly mistake each blade was 3 inches to long! making it 16.5 ft overall. I don't know how I managed to miss that one lol. When carving blades I leave a couple of inches extra on the end for clamping to the bench and then trim it to length when finished, measure twice and cut once comes to mind. At least this was easy to fix, I think I need to get new glasses or a large print rule!
The tower this machine sits on is a telescopic lattice tower that tilts on its ground post via a 6 ton electric winch, well half way up the winch decided to die and would neither go up or down
so I had to raise it the rest of the way with a set of chain blocks that where grossly overloaded and made all sorts of scary noises. This is not the way to raise a tower and will NOT be repeated! a new winch is on order.

So thats it up and running again at last, now I can get started to the next job on my list, a new free standing lattice tower for the 12 footer and of course the wife has a list of jobs the length of your arm for me as well, such is life.

Russell

[97fishmt]

Hi Russell,
I have had a winch fail also.
I replaced it with a grip hoist, kinda slow but
very safe and I feel comfortable working with
it.  It's no problem for my 65' lattice tower.
Stopping at any time is sure nice, and easy to
pull in cable or let it out.

Glad to hear you are back in business.

[Hilltopgrange]

Thankfully when the winch failed it still held if it had fell I think I would have walked away and started looking for a new hobby! I looked at the tirfor type winches but eventually settled on a recovery type for the front of my Landrover, it was the perfect excuse for a new toy. Eventually I hope to fit hydraulic cylinders to my towers, I have all the bits and bods to do it just need to find some time.
Regards Russell

[freejuice]

I had fitted several grease nipples for the yaw tube and bushing and pumped it full of grease but I think a few mods are required. I will machine the bushings to give a bit more slap and fit auto greasers to each bush. With this being a lattice tower I can climb it and grease it every couple of months and hopefully avoid a repeat performance.

Hi Russel,
what you experienced, I fear the most...the generator unable to turn.
I'm in the process of building a 17 footer, and I found about a 3 inch thrust bearing on ebay. ..this one is similar: http://cgi.ebay.com/51208-Thrust-Bearing-40-x-68-x-19-mm-Metric-Bearings-/130200363954?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item1e508be3b2

I used thrust bearings of this type to rifle barrels...essentially I would pull an oversized carbide button...sometimes .011-015 thousandths oversize through a 27 inch long blank. The thrust bearing would take a tremendous load, but never failed to twist at the rifling rate I ground the carbide button for....the carbide would sometimes snap in half but the thrust bearing never failed.
I'm really sold on these type of thrust bearings they are extremly smooth and can handle quite a load. I will  probaly machine a "nest" for the bearing, so as to keep it tracking in its groove and put it on top of my tower stub when the time arrives, along with a few grease fittings too!
 All the best,
 Gavin

[Hilltopgrange]

Hi Gavin
          those thrust bearings should be fine if you can keep them well lubricated. I have always used a simple disk of brass as a bushing and never had a problem. The main thrust bush on this machine was fine, it was the lower side thrust bushing that seized. The yaw tube is about 1/2in bigger in diameter than the mast stub so a strip of 4 x1/4 was welded around the stub mast to take out the side slop, I guess it was to good a fit. I have ground about an 1/8 of it and cut slots in it to reduce the surface area and allow grease to gather in the slots. I should have taken a few pics.
Regards Russell