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Forum Index : Windmills : Some experiences with Exmork wind turbine

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Bolty

Regular Member

Joined: 03/04/2008
Location: Australia
Posts: 81

Posted: 09:28pm 23 Feb 2010

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I bought a 1kW Exmork with 2.7 m diameter blades about 18 months ago very cheaply from China. The freight from Shanghai to Melbourne was only US $20. The cost from Melbourne to Adelaide was many times that!!!!!

It is a very rugged, and so far reliable machine. In my quest for more power from a very poor wind site, I fitted 5 m PVC blades. Massive over-size! The inevitable occurred, with a 25 m/s wind within 1 hour of erecting. The turbine brake could not control the massive power captured by the strong winds, and the turbine span out of control. At an estimated 600 rpm the blades exploded sending one flying 100 metres through the air. The other 2 blades bent and hit the pole, stopping immediately. The blades were totally destroyed. Luckily I live on a 2.5 Ha property, so the flying blade remained on my property with no other damage.

Despite the massive impact of the exploding blades, after re-fitting the original blades, everything works perfectly well again. Thus ended the first lesson on Greed by going for blades that were too big!!!!!!!!!

I guess that my turbine was spared this experience due to the massively strong shaft, which from memory is 42mm!

I have nothing but praise for this turbine kit. Everything was rugged! As an example the guy wires were 10 mm diam. I think that the price was only US $540 with pole and guys and freight to Melbourne.

KarlJ

Guru

Joined: 19/05/2008
Location: Australia
Posts: 1178

Posted: 06:26am 24 Feb 2010

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Bargain, I'm sure never to be repeated.
pity about your site, but for that price its a great garden ornament

Karl

Luck favours the well prepared

brucedownunder2
Guru

Joined: 14/09/2005
Location: Australia
Posts: 1548

Posted: 02:04am 25 Feb 2010

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Thanks Bolty for the post.

They are built like brick outhouses,mine is still on the testpole,,will complete the tracking ,take the tail off and hope to have a dry-as-a-bone inside . have not given up on drilling two small holes in the lowest parts when I get her down again ,,just to be sure???

my next F&P or LG will have one of them fancy tails ,,so compact...and small.

Thanks again

Bruce

Bushboy

Darren

Newbie

Joined: 13/07/2008
Location: Australia
Posts: 20

Posted: 02:25pm 26 Feb 2010

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Hi Guys I have one of these chineese mills on a 60' tower and had nothing but trouble with fancy tail.
I've pulled the tail apart and re-machined the 2 tapered cones trying to get it to track correctly.
Still the biggest problem.
Ive had 2 years runing out of it so far and only tracking problems so far.
If anyone has got a fix for the tail it would be great help.
Darren

brucedownunder2
Guru

Joined: 14/09/2005
Location: Australia
Posts: 1548

Posted: 08:38pm 26 Feb 2010

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Hi Darren,

Someone in a previous post had similar problems and Exmork discussed it with him .

It appeared he had the angle of the tail in the wrong position-there are 3 holes for the bolts. top one is for the single pivot bolt and the two bottom bolts holes are for the angle ...

They told him to bolt it at the 45 degree hole position .

Could you possibly post a photo of your tail set-up,( 60 feet is a long way ,but....)?.

Exmork has a forum ,Google that for other users experiences..

what size (output) is yours and what have you actually seen it produce. Is yours the 2.5Kw,?(previously marketed as the 2 Kw .

The 2.5Kw ,they reckon ,can produce up to 3.6Kw ???.

Bruce

Bushboy

Darren

Newbie

Joined: 13/07/2008
Location: Australia
Posts: 20

Posted: 10:57pm 26 Feb 2010

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Hi Bruce , The unit in question is a 500W 12volt unit I do have a 2 Kw unit as well but have not installed it yet.
I will take some pictures of it this week end and post them
I have tried all 3 hole positions and it does not make any difference.
The machine just never seems to be pionting the right direction.
I have other mills near by in the same paddock facing diferent ways to this one.
Darren

Bolty

Regular Member

Joined: 03/04/2008
Location: Australia
Posts: 81

Posted: 11:41pm 26 Feb 2010

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Hi Darren.

As mentioned mine is only the 1kW not 2.5 kW like yours. However by your description, the tail arrangement sounds the same as mine was originally albeit larger.
I live near Gordon (GWatPE) and he immediately recognized that the tail was far too heavy and like yours, it did not track very well. The excess weight meant that it would not furl early enough. Gordon explained that it was not worth chasing the high energy due to possible over-revving at high winds. Also at my site, the wind is very seldom over 10m/s. Thus it was considered better to forego the small amount of strong wind power in the interests of safety and reliability. To achieve this I cut my tail arm as close as possible to the pivot point, just where the twist became vertical again (around 25cm from the pivot) I then welded a 50 X 30 mm piece of tubing to the remaining cut tail arm. The new piece made the total length of the new tail about 400-500 mm longer than the original. As for the tail, I have a marine ply tapered shape that rises above the tail arm like a 747 tail plane. It is about 4 times the area of the original metal tail, and looks much better! Apart from weight increasing the furling point, I cannot see any disadvantages of having a massively larger area tail.

This has helped dramatically with tracking. As for furling, I never saw the original tail furl even in strong winds!. However the new lighter tail furls nicely before the wind gets too strong. I would be amazed if I am losing as much as 3 kWhrs a year through the earlier furling!

KarlJ

Guru

Joined: 19/05/2008
Location: Australia
Posts: 1178

Posted: 04:35am 27 Feb 2010

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pics Bolty pics!

Luck favours the well prepared

Bolty

Regular Member

Joined: 03/04/2008
Location: Australia
Posts: 81

Posted: 12:47pm 01 Mar 2010

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Here are two photos!

Darren

Newbie

Joined: 13/07/2008
Location: Australia
Posts: 20

Posted: 12:56pm 01 Mar 2010

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Thanks for the pics bolty
Mine is very different in the tail section. I forgot to take my camera with me on saturday but I have some pics at work so I will post them tommorrow.
Darren
PS I like your Tail.

brucedownunder2
Guru

Joined: 14/09/2005
Location: Australia
Posts: 1548

Posted: 08:00pm 01 Mar 2010

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Hi Crew,

Yes,that boom is the pivoting type,smaller machine than the 2.5Kw. It's boom is at an angle (offset) fixed. The fin blade is fitted to a 45 degree sloping axle ,the fin furling on this axle . I've never seen this before ,but if it works,and I'm sure it does, then it could be a different way of thinking for the rest of our mills. I expect there are advantages in that less reaction around the gennie end,the only movement is out at the fin.. We'll see.

as these are very heavy for one man lift,65Kw , I picked up a hospital person mover from the junk shop,(lucky,i guess) $10. Will bolt a little boat winch on it and extend the boom ,should be able to move the gennie around the concrete to and from the workshop ,easy..says a safe working load of 150Kg.

Bruce

Bushboy

Darren

Newbie

Joined: 13/07/2008
Location: Australia
Posts: 20

Posted: 10:40am 02 Mar 2010

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Hi guys ive acttched some pics for for you all as well as Karl
Darren