Author Topic: turbine rocking (Read 3129 times)

Ballyk · « **on:** February 09, 2010, 03:20:54 AM »

hello all.

Unlike the majority of you there I dont have the technical ability to build a turbine so I went off and bought a 2KW turbine,controller and inverter from Exmork in China. I also bought 500watts of solar. i have had a few problems with the turbine. The solar is fine. On a good windy day I will get 25/30 amps at 48 volts from the charge controller and this will keep my forklift battery charged up and this in turn provides about 60% of my house electricity.It has the ability to reduce my bill from 250 to around 100. I am in ireland where the cost per unit is very high.

The problem with the turbine is as follows. When it starts turning just before it gets to a good speed the stayed pole starts to rock quite a bit. I have it bolted to my shed at 3mts, stayed at 6mts and at 9.5mts. It is 12 mts in total. i have read the forum on balancing the turbine but I am wondering if balance could do this as it is quite severe. I am noy talking a little vibration here! I was so bad thet the tail pole sheared and the vane fell off through the roof of my shed. I got new parts from China with no problems but it is still at it.

Any help I can get would be very helpful.

Regards to all

wpowokal · « **Reply #1 on:** February 09, 2010, 04:20:02 AM »

Sounds like a tracking problem to me, tracking is when each blade tip follows each other, meaning front to rear. Done lowered and turning the blades past a marker and adjusting them until they track true.

Allan and not even an Irish joke

angus · « **Reply #2 on:** February 09, 2010, 05:54:40 AM »

As has been pointed out it could be a tracking problem.

The blades need to track within about 5mm of each other.

To check this and to rectify any miss-alignment you would need to lower the mill and do some tracking alignment checks on the blades- this is not difficult .

It basically involves spinning the blades by hand and checking for any blade runout and adjusting for this runout.

There may however be another problem.

You say that the mill "just before it gets to a good speed starts to rock a bit", and if I am reading you correctly the mill settles down after this.

To me this suggests "harmonic distortion".

All structures, buildings, bridges, towers and wind mills have a harmonic frequency.

Any vibrations that are intune with this frequency add to and magnify the vibration of the stucture and -in the extreme- lead to the collapse of the structure.

But here is the good news.It is easily fixed.

Try adjusting a few things.

If you bring the mill down for checking, raise the 6 metre stays to say 7 metres and maybe put in an extra set of stays at say 4 metres. Also the fixed "bolted" connection to your shed may be a problem. Consider making this connection a little more flexible. Anything that prevents vibrations from accumulating is a good thing.

Engineers plan/design for this all the time.

Hope this helps.

Regards Angus (The older I get , the better I was).

Flux · « **Reply #3 on:** February 09, 2010, 08:16:53 AM »

Check balance and tracking, both cause this problem. It's best to try to reduce the exciting force to a minimum first but Angus is correct that if it only shows at one speed you may have resonance making things much worse.

Flux

Ballyk · « **Reply #4 on:** February 09, 2010, 09:47:14 AM »

Thanks for the replies.

just a few questions on it still. When you say "tracking and runout"are you talking about one blade being foreward or behind the others as the "disc" spins or is it the lengthe of the blades not being the same? I am still a bit confused here.

regards

Ballyk · « **Reply #5 on:** February 09, 2010, 09:55:52 AM »

I dont think its resonance/harmonics but I could be wrong. the bracket on the shed is not absolutely ridgid. I have thick rubber blocks inside the bracket and there is some movement in it.

When you say runout are you talking about the blades following each other around the same "disc". Is one blade foreward or behind the others in this disc.

would balance do this also.

regards.

Flux · « **Reply #6 on:** February 09, 2010, 09:57:49 AM »

Yes, all the tips should be in one plane. Just turn it slowly and check each against a reference point.

Flux

galeforce jones · « **Reply #7 on:** February 09, 2010, 01:58:34 PM »

Where abouts in Ireland are you? I would be interested in seeing your setup and maybe help you with tracking and balanceing your turbine if you are not to far away. I'm from Cobh, Co. Cork and built a few of hugh piggot design at the moment I am building 3.6 turbine. You can email me at jones-casey@live.com

SparWeb · « **Reply #8 on:** February 09, 2010, 10:38:27 PM »

I've personally seen an Exmork (5kW) being assembled. The blades are bolted into slots on the hub, meaning the installer must set the blade pitch carefully. A mistake at that stage could have caused the problem (falls under the "tracking" category).

It seems Exmork changed their blade construction a few years ago, meaning that a new blade is not interchangeable with one old blade - the whole set must be replaced.

I think a fellow from Norway has posted some info about his 2kW Exmork on this board. His name escapes me now, but he may have some hints for you.

I'd appreciate it if you could post a follow-up of how you resolve the problem. I'd also like to know about your observations of the Exmork's furling. The tail on the 5kW seems too small to my eye, so I am suspicious of it.

... and welcome to the board!

Ballyk · « **Reply #9 on:** February 10, 2010, 01:53:47 AM »

hello Steven,

I did have some problems with the tail as I mentioned. The main was that it fell off and went down through the roof of the shed. The first one was that the turbine was furling way too soon and I was getting surges in output. It would go fron 5anps to 25 amps but never stay steady. These amps are chargeing amps fron the controler. I contacted exmork and they said that I probably had the tail set up wrong. There are two settings on it and they told me to change it to the 60degree one. This seemed to work. The issue now is that I havent really seen it furl since. I know two people with the 5KW in this area and they dont seen to be having any problems.

Regards,

eamonn Coady

Waterford

SparWeb · « **Reply #10 on:** February 10, 2010, 11:36:59 AM »

Sorry to hear about your shed.

I was unaware that the tail could be adjusted. Would that be an adjustment from 90 degrees (hinge axis pointing straight up) to 60 degrees (hinge axis swept back)? Or would it adjust the point where the fin stops turning, inclined at 60 degrees versus something else when it furls?

Thanks for the extra info.

BruceDownunder · « **Reply #11 on:** February 10, 2010, 01:47:45 PM »

Hello, I've just taken delivery of the 2.5Kw ..

I've set a testpole and will balance and do the tracking before raising it.

Have tried yesterday and today to resize the photo's into fieldlines ,have given up after 2 hours.mine is 165kb.

if you want to see the testpole have a look in my irc phot album ...someone will help you get there,my brain is hurting...

Bruce

Ballyk · « **Reply #12 on:** February 11, 2010, 01:30:47 AM »

hello Stephen,

There are only two positions that the tail can be put in. I checked with exmork and they sent me a picture guide to the settings. I cant paste it to this mail so if you send me an email to eamonncoady@eircom.net I will forward it to you. They also sent me a replacement tail pole last week. This one only has one setting but if I decide to use it I will drill the second one.

I had a long call from Ml.Jones in Cobh arising from this conversation and we are meeting up next weekent to track and balance my turbine so hopefully I will get to the botton of it.

Regards,

Eamonn Coady

Ballyk · « **Reply #13 on:** February 11, 2010, 01:37:26 AM »

Hello Bruce,

You obviously got the new model which is 2.5KW. just one tio for you . Spray the brushes on the slip rings with some kind of electrical contact spray before you put it up. These turbines all seemingly have a tendency to "squeal" a bit as they turn on the sliprings. I figured out it was getting a little damp so I sprayed the rings etc with WD40 and it worked. I also made up a gasket with an old inner tube and put it between the tail and the body where the 4 allan bolts go, as I was getting a little water in there. it seems to have done the trick. no squealing now.

Regards,

Eamonn Coady

Jimmy D · « **Reply #14 on:** February 12, 2010, 06:35:23 AM »

Hello Ballyk,

If the thing worked fine before and this problem has just sort of developed it may have happened to me also.

I have fiberglas blades which were balanced perfectly until one day they started to really shake the tower

I thought maybe I'd thrown off some or all balancing weights.

I took it down to investigate and found no problems. Lucky for me it was perfectly quiet and calm and really by chance when rotating the unit I heard the slightist tricle of water.

It had been calm and rainy the last few days and the blade facing down had let water into the blade through the root face. I drilled a 3/16" hole through the tip towards the root and got about 25ml of water out...about a tablespoon. Eureka! for balance reasons I drilled the others the same. Fixed.

Check it out, maybe you'll be this lucky.

Regards Jim

BruceDownunder · « **Reply #15 on:** February 12, 2010, 02:05:49 PM »

Hi Eamonn,,

Jim may have answered your question .. I've noticed ,on my testpole , that maybe small holes should be drilled in the base of the forward and rear castings,carefully, to let any water out ,just maybe 3/16 holes.

The blades ,maybe the same in the ends ..

I'll lubricate the brushes as you suggested,thanks.

I'm still working on the balancing and tracking could let you know progress later

Bruce.

Ballyk · « **Reply #16 on:** February 13, 2010, 11:08:37 AM »

hello jim.

Im on the south coadt of Ireland. We were up to our knees in water this year so maybe you have hit the nail on the head.

I broke my tirfur so when I get that fixed I will drill holes in the blades,the casings,and the tail pole. I will then put a coulpe of coats of good UV resistant acryllic paint on them. I will balance the blades and track them and them.

I have a busy few days ahead of me. Thank god for the recession!!!! I have a lot more time on my hands.

Regards,

Eamonn

Ballyk · « **Reply #17 on:** February 13, 2010, 11:09:12 AM »

hello jim.

Im on the south coadt of Ireland. We were up to our knees in water this year so maybe you have hit the nail on the head.

I broke my tirfur so when I get that fixed I will drill holes in the blades,the casings,and the tail pole. I will then put a coulpe of coats of good UV resistant acryllic paint on them. I will balance the blades and track them and them.

I have a busy few days ahead of me. Thank god for the recession!!!! I have a lot more time on my hands.

Regards,

Eamonn

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