EOLtec Scirocco feathering problem

[Donald Mainland]

I have a EOLtec Scirocco (6kW) which has operated successfully in a windy region for over two years, but has now developed a feathering problem. A few weeks ago it stopped feathering because something became locked – probably the bearings – and it could only be stopped because it freed itself long enough to use the lever to feather it to a standstill.

It still has to be inspected by the installer since this happened over the holiday period.

Has anyone had a similar problem with the Scirocco? Any ideas of the likely cause would be welcome.

[Rob Beckers]

Hi Donald,

Where are you located?

I've seen two Sciroccos with similar problems; In one case a postmortem revealed heavy rust inside the slewing rings that allow the blades to change pitch. This made those rings turn with heavy resistance, locking the pitch. It seems water got in (despite that they have seals, and are protected by the nose cone). In the other case we never were able to determine the cause, we replaced the entire hub with the pitch control mechanism and slewing rings.

Eoltec says this is a rare issue (even more rare is if you can't force the blades to the stall position with the manual brake handle, that would mean things are really locked up inside! Something I've not seen before). Less rare are slewing rings that bind right off the bat. After installation the blades will not properly move to the stall position, though the slewing rings rotate freely when tested before installation. Eoltec is still figuring out the cause (likely something is deforming just enough when the bolts are tightened to lock the rollers inside those slewing rings).

-RoB-

[Donald Mainland]

Hi Rob,

Thanks for the reply and info. I’m in Orkney, where a lot of the Scirocco testing was carried out.

It looks like my installer is waiting for a response from France before doing anything.
I think that there’s been a bit of an issue with the blade-feathering being over-active in strong winds. I’ve certainly noticed that.

Meantime I’m losing out as there’s been a lot of wind this last few weeks; a near neighbour is reporting around 100 kWh/ day so I’m hoping that things will be sorted out soon.

Bye the way, what is the guarantee situation if an installer gives less than the 5 years mentioned by eoltec? The UK ‘Sale of Goods Act’ has an item called durability which I take is related to the likely lifetime of the item. For example, if an item with a likely lifetime of 7 years goes faulty within 1 year and 1 day, it is up to the seller to repair it no matter what the guarantee says. I wonder what the equivalent time is for the Scirocco.

Thanks again and congrats. for an excellent site. I’ll keep you posted – this could be a long story!

DM

[Rob Beckers]

Donald, consumer laws regarding warranty vary from country to country. The situation over here (North America) is that the manufacturer is ultimately liable to live up to the promised warranty, not the installer. However, that doesn't stop anyone from suing an installer (and possibly win) if something went wrong and the item doesn't live up to its billing. Eoltec has been quite responsive in sending out replacement parts in case the local installer is not helping (of course you'd end up doing the work yourself). So you may consider contacting them directly.

I'm aware of the issue with loss of power in case of extreme winds, where the pitch control will move the blades too far to the stall position, stabilizing around 3.5kW rather than the 6kW. That seems to happen in very high winds only, since nobody on this continent has reported anything like it. Eoltec is reportedly working hard to find a fix. Of course, as wind turbine enthusiasts we can only dream of the wind speeds and their frequency that you have on Orkney!! Except for a very few coastal locations there's nothing remotely like it anywhere here.

-RoB-

P.S. My favourite scotch comes from Orkney; Highland Park, made in Kirkwall. I'm hoping to go on pilgrimage some day and visit all those distilleries in Scotland, including Orkney... :cool:

[Donald Mainland]

Rob, you are obviously a man of refined tastes! I hope that you will drop by us when you come to Orkney – to see a static Scirocco and sample some single malt.

Still stalemate here, between the installer and eoltec I assume. Various agencies are becoming involved so it’s difficult to see what the outcome is going to be. I’ve emailed eoltec regarding the supply of spare parts to an individual in case it comes down to me having to repair it myself.

As far as the pitch control is concerned, the main problem seems to be that a strong gust of wind causes it to over-feather and suddenly slow down; this is followed by a recovery, only for the whole process to repeat. Apart from a loss of output, this must put an extra strain on the turbine.

An amateur’s observation might be that the control system requires damping, or at least more damping than it has at the moment but time will tell.

[David Simms]

Could someone enlighten me re. the construction of the slewing rings ? From the photos I've examined, it appears that the blades would sit in/on a ring that rotates within another and that these would probably rotate a cam that pushes on the spider and spring.

My experience with the old Jacobs flyball governor has taught me that the blades should never be allowed to rotate in either ball bearings or roller bearings. The small vibrations on the blade root will always wear the rollers into the races so that they sit in small groves. On the other hand, bushings never show this problem because there are no pressure points.

[Rob Beckers]

David, the slewing rings contain cylindrical rollers. They are supposed to be designed for large axial forces, as well as radial loads. I'm no structural/mechanical engineer, so I can't comment, though I do know the engineer at Eoltec, and he seems to know very well what he is doing.

The issue seems to have more to do with manufacture/source of those slewing rings and less with their suitability. The slewing rings used to work fine, and have been a problem since Eoltec changed suppliers for them (and to their defense, they did not have a choice in the matter, their original supplier was not going to continue supplying them).

-RoB-

[Donald Mainland]

Hi Rob,

Re my original post at the top, my Scirocco has been performing well since its hiccup at the end of last year.

I'm interested in fine tuning its response to strong gusts via the gas filled ram screwed into the hub - a modification produced by Eoltec shortly after installation in 2009. The ram is about 8" long and it has a stiffness adjustment at the outer end. I've been told that it should be screwed in so that 31+/-1 mm protrudes beyond the hub and that the stiffness setting (1-9 scale) determines the speed of response to gust feathering. Have you come across this modification and, if so, can you tell me a bit more about it please?

Thanks,

Donald.

[Rob Beckers]

Hi Donald,

So the blade slewing rings were replaced?
Very recently Eoltec indicated they (finally) resolved the slewing ring issues. This had to do with manufacturing rather than the design.

The Scirocco turbines I've seen do not have the gas filled spring/ram, so I cannot say much about it. I know there was some undesired dynamic behavior during very high winds, that could set up oscillations, and assume that's why the gas spring was added, to provide some damping. We never had that happen with the Sciroccos installed in North America (then again, we don't really have any locations with winds like you would see on the Orkney Islands). If it's working well at its current setting I would leave it alone.

-RoB-

[Donald Mainland]

Hi Rob,

No, the issue was related to the damper, not the slew rings, although I know that they have caused a problem to some.

I know I should take your advice and leave well alone but I might try to edge a little nearer to perfection by very careful fiddling!

Donald.

[Eoin McMahon]

Hi I would like to tell you all about my experience with the Eoltec machine. I realise that alot of people do not like to hear negative things about any small wind turbine but this is all fact and people should be aware of it. My Eoltec 6KW machine was installed in december 2007 and after a couple of months had to be taken down to galvanise the nacelle and fix strengthening gussets to the tail. A year and a half after installation the slewing bearing disintegrated. A year after that the bolts holding the rotor assy to the generator sheared and the rotor fell to the ground. We were lucky no one was killed. On inspection I found the blades were split down the seam, damage not caused by the impact. I found out Eoltec were aware of this issue for 2 years before my failure occurred and I was not informed.
Eoltec would not reply to e-mails or calls on the issue. I was told through a different supplier that they blamed my installer and the height of the pole. I believed them until I found out the exact same failures have occurred on countless machines on varying pole heights, on varying sites and installed by a number of installers and in multiple countries. This points directly at the design and manufacture of the machine.
Eoltec will not take any responsibility for their machine and their part in this situation.
Their machine is dangerous and should not be on the market. They have not solved the root causes of the failures and most certainly have not supported their machine in a manner that is becoming of a responsible company. If anyone is thinking of buying one of these machines hopefully you will see this post before you do and think twice about it.

[Mark Knopf]

Greetings Donald & Rob,
I was browsing around and found this thread quite by accident. I'm located in the US Virgin Islands and have had my turbine operating for 19 months. I have no complaints with this turbine other than the the same problem as Donald. I have exactly the same problem as Donald in high winds, with the overfeathering and recovery cycles that are seemingly endless. It drastically impacts my production as I produce more in 15- 20KTs of wind than in 20-30KTs. This is the first that I've heard of a dampner in the furling system but it is what I asked Rob Beckers about over a year ago. Rob has been a great help through the initial startup and has a wealth of information on his website as well. I recently serviced my turbine and checked the slewing bearings and all seems to be in order so far. Donald, have you attempted adjusting the dampner and is it simply a bolt in unit as it sounds like exactly what I need here in our strong trade winds. Thanks in Advance Mark

[Donald Mainland]

Hi Mark,

Good to hear from you - it sounds as if you have plenty of wind there too, and I know that it is very annoying not to get the full benefit from it.

My Eoltec continues to perform pretty well but I can't see the quoted estimated lifetime of 20 years without a few replacements, most likely bearings.

As far as I can make out, the damper is gas filled and can be adjusted in two ways; the first is the distance that it is screwed into the hub. I think that this will determine when it takes effect, the farther in the sooner it will prevent feathering; the second is a stiffness adjustment which will set the damping effect. This is set by a screw on the end numbered 1 to 9, with nine having least effect. Bear in mind that I haven't been told this by Eoltec, but just what I've heard from other Eoltec owners in the area and deduced for myself.

The damper certainly makes a difference but I think that the settings should be different for every site, and probably for different seasons on the same site. Ideally I should start a program of adjustments but as long as it is working pretty well on the existing settings I think I'll leave things along - the maximum 24 hour average I've got is 5.28kW, swinging between 6.2 and 4.4 kW.

A recent new behaviour I've noticed is the output sticking at a low of about 1 kW in very strong winds, with occasional short bursts of full power. I suspect that this may be caused by the slew bearings sticking in a feathered position, but that's another story!
It would be worth your while getting a damper to try out. It can easily be removed if you're not happy with it. If you do get one, be sure to use locking fluid on the attaching nut for if that loosens, there is a danger that the unit will screw inwards and prevent feathering.

I wish you good luck and look forward to hearing from you again.

Best regards,

Donald

[Rob Beckers]

Mark, welcome to the forum! I recall we talked on the phone once or twice when you were installing your system.

The slewing rings used at the blade root have shown to be the weak link in the Scirocco. Any stick-slip behavior will set up those oscillations, and can make the blades stick in the low-power position (or worse, if they stick in the high-power position the turbine will overspeed). Eoltec says they now have better slewing rings, so Donald, you could try and get them replaced.

-RoB-

[Donald Mainland]

Rob,

Happy New Year and thanks for that info. Yes I have suspected for some time that the slewing ring bearings are critical to the whole operation and have been a source of problems.

My Eoltec agent is now based in Shetland, our neighbouring island group, and he has told me that some Eoltec owners there have also been reporting this low output problem. I have already prepared him for my possible need for new bearings so in the meantime I 'll just hope and pray that any sticking is in the low output position.

Donald.

[Mark Knopf]

Greetings Donald and Rob,
I'd tend to agree that this turbine will probably need some serious Maintenance to get the 20 years but I don't know of any machinery that will run 175,000 hours in some pretty extreme conditions without major maintenance. I think we're all ready for the forseeable issues it's the others that are annoying.
Thanks for the feedback about the dampner Donald, I'll try to get one from the factory, if that fails I might need to enlist Robs help. I'll keep you posted. Thanks Mark

[Rob Beckers]

Mark, just to let you know: I don't have those dampers. None of the turbines we receive from Eoltec have them.

Your point regarding maintenance and repairs is right on the money. Anyone that installs a wind turbine should expect that there will be the need for not only annual inspections/maintenance, but parts will fail as well. The "20-year life span" that manufacturers claim (Eoltec is not the only one) is somewhat misleading, and should be taken in the same meaning as with a car; yes, the turbine can be kept working for that duration, but you'll be replacing parts along the way. Hopefully (normally) the parts that need replacing are limited to those that see movement, such as bearings, slewing rings, and possibly slip rings. Hopefully the really expensive bits such as the alternator and blades will stay the course. Owners should budget for repairs though when doing cost/benefit calculations. Expecting anything that is out in the weather every day of the year, and that has moving parts, to work flawlessly for 20 years is just not realistic.

-RoB-

[Donald Mainland]

After three and a half year's running (63000 kWHr), our turbine's slew bearings have been replaced by new ones obtained from Eoltec via our local agent. The original ones were showing increasing lateral movement at the blade tips - checked at servicing - and each of the seals had broken.

The turbine now runs better than it ever has with much reduced rotational surges in strong wind and it is quieter - less groaning in light winds and less slapping in strong ones. Either the original bearings were not quite up to requirements or the new ones are better.

It will be some time before we know whether the production has been improved as well, but it gives some peace of mind to know that it is running better.

[Donald Mainland]

Our Eoltec turbine has just had it's 7th anniversary and has continued to perform flawlessly after having all the bearings and damper replaced - an average of 18750 kWhr pa.
A friend, who also has a Eoltec, and I help each other to service them twice an year. We use a 3:1 block reduction and a tractor to lower and raise the masts, but retain a turfer and steel hawser as a backup.
Apart from having to patch a few imperfections on the blades and cowl, we have had no requirement for repairs. (I hope I am not inviting disaster by saying all this)

I would welcome comments from other Eoltec users.

[Jean-Louis Papel]

Hello Donald,
I have followed your success-story with the Scirocco 6kW, congratulations !
I would be very interested to know about the behaviour and life-time of multiblades american low-speed windmills, if you know any of them, under the very strong winds in North Scotland.

I have a project for a public-use building specifically designed to be heated by windpower. Scotland is a target location for my project, not only because of the high winds but also for the short duration of the day-time in winter (otherwise solar-power is a lot more competitive and straight forward).

I opened a thread in November on this forum about this project under high latitudes.

Bon vent ! as we say in France.

[Donald Mainland]

Hello Jean-Louis,

Thank you for your reply. I'm afraid I don't know of any of the windmills you mentioned.

The problem with some of the turbines developed in more benign climates is that they haven't been subjected during development and testing to the environmental problems which often go along with extremely windy regions - in the North of Scotland we can have calm sunny spells then heavy, driving rain, gusting gales, salt spray etc. In other words, the weather can be both extreme and very changeable.

I wish you good luck with your project. Make sure that you use a rebust and suitably tested machine and you should enjoy a good return.

I look forward to hearing how you get on.

[Joke Evers]

I would be very interested to know about the behaviour and life-time of multiblades american low-speed windmills, .
Hi Jean Louis,

I don't have actual experience with the American "windrose" type windmills myself , but in the Netherlands a few people try to maintain/keep alive what is left of the huge number of wind-driven water pumps...that kept our low lands dry ...before being replaced by steam and later diesel pumps (...)
http://www.windmotoren-friesland.nl/
(in Dutch only)

What I do know is that this type of windmill will perform excellent under non-ideal circumstances (like turbulence)... and many types had robust self-regulating control systems avoiding storm damage .
(note: these windmills performed nearly always unattended on "isolated" locations)

If one day our Chinese "wind turbine" should fail , we will certainly rebuild it with an American -type multi blade rotor !!

kind regards,
Joke

[Jean-Louis Papel]

Hello Joke,

Thanks a lot for your post.

I also have been passionate by old windmills for water-pumping from Bollée in France in the 1900's.
I put here some links about them and their renovation (for a very few of them).
I am not sure the technical solution used by Bollée (Stator + Rotor) is the best one for their efficiency, but they are very aesthetical and smart.

http://www.archivingindustry.com/Eolienne/

http://nicole.fond-ecran-image.com/blog-photo/category/de-merveilleux-sites-de-ma-touraine/leolienne-bollee-a-esvres-sur-indre-en-touraine/

In reality in my project I plan to manufacture a DIY 5m diameter / 30 blades windmill based on the calculations I could made using the very scarse documentation available, particularly relative to the blades' profile characteristics of simple curved steel-sheets.
I could work-out the optimum width and static pitch angle relative to each radius of the blades.
You may see the details on my blog if you are interested (see my thread in this same forum).

Bon vent !

[Jean-Louis Papel]

Hello Jean-Louis,

The problem with some of the turbines developed in more benign climates is that they haven't been subjected during development and testing to the environmental problems which often go along with extremely windy regions - in the North of Scotland .

Hello again Donald,

I would like to make more simulations regarding the autonomy in heating a building all over the year in Scotland, using windpower, a water-stirrer and a huge seasonal water storage.
Although trying very hard, I could not find the detailed Weibull parameters of the wind distribution, for a place anywhere in Scotland, on a month per month basis.
Do you know where I could find such an information ?

Best regards,

Jean-Louis

[Donald Mainland]

Hello Jean-Louis,

I'm afraid I can't help you with that. Like you, I've searched and have been unable to find detailed data. Sorry.

Best regards,

Donald

[Joke Evers]

Although trying very hard, I could not find the detailed Weibull parameters of the wind distribution, for a place anywhere in Scotland, on a month per month basis.
Do you know where I could find such an information ?


This seems to provide the info, although the program & database are not free !

http://www.wind-power-program.com/windspeedV2i_video.htm

Joke

[Jean-Louis Papel]

Thank you Joke for your URL info.

Unfortunately this software does not give the information I am after.
Full of hopes, I had purchased this database a few months ago. It has a very pleasant interface, but it only informs about the "average" wind-speed everywhere in the UK, at various heights above ground.

Unfortunately, it does not give the Weibull parameters that would allow for instance to know the probability of occurrence of high windspeeds.
In my project the windmill can operate under very strong winds with a very high power output (without feathering), so that even if their probability is low, the overall participation to the heating storage is still significative.

Another point is that it does not give these parameters for each month of the year. In my project, and in order to simulate the autonomy of heating of the building all over the year, I have to know with precision the heat-flows (inputs and outputs) of the seasonal water storage.
For instance the solar-panels heat-flows in summer are very important and if the storage insulation is sufficient, some of this heat will still be available for the next winter.
It is also precious to know wether the winds are stronger in winter, when the heating requirements for the building are maximum.

In my project, the underground seasonal water storage is huge (720 cubic-meters), with an external insulation wall 1m-thick. The tilt-angle of the 160m² heating solar panels on the roof, privilegiate summer contributions to the storage. The tilt-angle of the 3x21m² photovoltaic solar-panels on the roof, privilegiate winter contributions in order to feed the heat-pumps that extract the last calories of the storage at the end of the winter.

This project is for a community building in a remote place, preferably in a country under high latitudes (Scotland, Denmark, Canada, Patagonia, New-Zealand etc ...) where winds are strong and daylight-time very short in winter. In other countries, windpower contributions are not significant versus solar contributions and the building of my project could be autonomous only with the solar panels.

Full details in my blog: www.windmill-for-heating-buildings.blogspot.com


Bon vent for your own projects Joke !