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Author Topic: Evoco 10 failures  (Read 5487 times)
bielec
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« on: January 07, 2012, 11:50:12 PM »

There have been a number of Evoco 10 failures recently, see..

http://www.clickgreen.org.uk/news/national-news/123009-evoco-issues-alert-to-shut-down-all-its-wind-turbines-after-series-of-failures.html

There was a previous issue with blade mount brackets cracking, which was fixed. Now this.  If you look at the pictures, it is clearly the blade proper which has broken, not the mouting bracket.

I don't like the fact that some units are not braking to a standstill either.

Does this mean that the brackets are now holding and the blades are the next weakest part?

They advertise survival to 135mph !  Obviously a theoretical figure.

Anybody have better info?
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stannn
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« Reply #1 on: January 08, 2012, 10:54:57 AM »

For large machines, the blades, and indeed the whole structure, are always modelled using computer finite element analysis to show where the stress hot-spots are located, for each load case. The failures indicate that either:
the design loads used were too low, or
the modelling of the blades was inaccurate, or
the model mesh was not fine enough in critical areas, or
the blades were not manufactured correctly to the design.
I think that the design cases should accept the fact that brake failure can happen and that the machine will not disintegrate under such circumstances
Stan
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2.45 kWp PV (Navitron supply), 40 evacuated tubes (Navitron supply), Clearview 650 log burner with back-boiler heating cottage and water, 2 off 50W border collies, 1 off 35W cat, 1 off 25W cat.
bielec
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« Reply #2 on: January 08, 2012, 05:41:39 PM »

Stannn   I absolutely agree.

Apparently the thinking is that there are unexpected gyroscopic loads due to sudden yawing during high winds.   The fix is a yaw damper.   I hope it works because I am too far advanced in installing one to pull out.

Why didn't  this show up during MCS testing? 
MCS appears to function well in producing a monopoly for big manufacturers but patently doesn't assure quality for the consumer and will undoubtedly slow down the rectification of faults because of red tape.
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wookey
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« Reply #3 on: January 08, 2012, 10:16:20 PM »

I guess that gemserve's (they do the MCS testing, I think?) wind-tunnel doesn't go fast enough to break them, or more likely doesn't produce the really gusty, twisting wind of real storms that induces the pruported failure mode?
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Wookey
charlieb
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« Reply #4 on: January 09, 2012, 06:09:45 PM »

Ditto Bielec.  Somehow makes me feel better that someone else is in the same boat.   
Despite the fact I'm now paying interest of 700 a month on mortgage extension I have to say I was pretty glad the turbine didn't get installed before Christmas as originally planned (tens of trees down, and few buildings round here survived with zero damage).    My installers are being very efficient at keeping us informed, and apparently Evoco are being very open with all their re-sellers and offering compensation to turbine owners that are awaiting the new damping mechanism. (Remains to be seen whether that'll apply to people like me who have a foundation in and turbine delivered, but not up in the sky yet).
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bielec
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« Reply #5 on: February 27, 2012, 06:44:40 PM »

Well I got my Evoco with the latest mods. which include a yaw brake damper and carbon fiber blades.  The first 4 days have produced 675 KWh and it is going strong today.  I am well pleased so far. See screenshot.

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charlieb
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« Reply #6 on: February 28, 2012, 09:28:14 AM »

Good to hear it Bielec.  Mine is up (I'd attach photos if I could get them off my phone onto work laptop) and looking handsome. AWaiting it's yaw dampener now - I haven't heard anythging about cf blades.
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bielec
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« Reply #7 on: March 20, 2012, 05:08:35 PM »

The data logging above was done by a program I wrote myself which takes readings from a clamp meter on the turbine supply cable.  I noticed another post which implied this was an Evoco Logger. It is not.

My turbine has sat "upwind" turning slowly backwards the last two days and although it yaws back and forth it wants to stay like this.  I beleive a couple of other owners have had this problem too so I await  advice from Evoco.  It was not possible to make it flip by stopping and starting. Very frustrating in 25mph wind.
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charlieb
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« Reply #8 on: March 20, 2012, 09:21:04 PM »

I feel your frustration Bielec.   Glad to say mine's been keeping studiously downwind (although making the odd ominously mechanical noise).
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gavkay
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« Reply #9 on: March 31, 2012, 11:05:10 AM »

Hi  we have an Evoco on a windy site on the North Coast Scotland and have long history of problem solving but now with the Yaw Damper we've turned it into a upwind turbine.  Gets more and more easily stuck and hasn't turned for days.  Winds at 9.2ms with turbine facing into the wind at the moment, refuses to flip round.  Has yours 'bedded in' and come out of retirement.  Anyone got the yaw dampener working?  need to know how tight this dampener has to be. 
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charlieb
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« Reply #10 on: April 02, 2012, 01:28:25 PM »

Mine went in with the yaw dampener already installed  (having sat since New Year waiting for it to be delivered) so I wouldn't say it's had any time for 'bedding in'. I'm not there that often, but every time I have been the turbine's been downwind as expected.   Installers are out to do final tidy-up this week, so they should be able to report on whether the noise is ominous or not (although there's no wind, so maybe not).
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bielec
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« Reply #11 on: April 02, 2012, 08:52:54 PM »

My unit spent three and a half days upwind the last time and that was in good 25mph wind.  It finally flipped back when the wind died down in the west and returned in the east.  I would expect more of that behaviour in the coming lighter summer winds.      It has also developed a creaking noise which changes to a schreech when it yaws.  My agent assures me it is nothing to worry about. I think it is the damper brake pads making  a brake squeal.  I have done 4340KWh since 21st Feb which is an average of over 100KWh per day even with the lost days.
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madmax
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« Reply #12 on: February 10, 2021, 10:15:35 AM »











new pitch bearings manufactured in Poland - avialable - asking price 1500e per bearing
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