Wind Turbine repair

[Gareth J]

I'll do a bit of research and come back to you on the bearing arrangement.

I wouldn't worry about it. Islander has repaired his now, should be good for a decade. And I don't intend to do a DIY replacement unless I really have to.

 

[Gareth J]

At ~20yrs, how are the leading edges of the blades holding up? Mine get really pitted. Most years I fill the worst of them with body filler and paint something over the worst bits. Last summer I gave the whole of the blades a rub down, after ding repairs and gave them a coat of clear lacquer. It's surprising how much quieter it is a low speeds with cleaned and smooth blades.

I don't hold out a lot of hope for the repairs, as experience says there are always more to do the following year. This summer I int6to try some 2k clear lacquer. May be a little more hard-wearing.

A repair I had to do ~5 years ago was to repair the tail boom tubes. The mounting point for the fore end of the tail fin had rusted very thin. I repainted the tail at the time and replaced all the bolts on the tail and cowling with stainless as the rust staining everywhere wound me up.

 

[Islander71]

The blades are in good condition, but are not the original ones. My turbine was the first put up on an exposed Scottish site within a mile or so from the sea, and was used to some extent as a testbed. Improved blades with an small anti-stall strip were later fitted complete with a narrow protective film on the leading edge, as was the rubber bush mounted tail fin replacing the rigid earlier fin which could cause fracture of the tail booms where they bolt to the top yaw box. Another later improvement was changing the earlier steel yoke end of the torque pitching mechanism to having ceramic bushes. The early ones had to be religiously greased, yet still wore quickly. I was given the connecting cable to connect the inverters to a computer with the necessary computer program to be able to adjust the inverter parameters - there are hundreds of them that can be altered! Periodically I would be asked to alter a parameter and note any change. Some I understood, like cut-in voltage or ramp-up speed or maximum output, but much was above my head.
The guys who set up Iskra were extremely enthusiastic about small scale wind power. They had all previously worked for Carter Wind Industries an American outfit I believe who were developing a large turbine which I think had some problems ,in the early days of wind development. This was taken over by an Indian owner who received large grant funding from the UK government to fix the problems. He simply shipped the entire works and development to India, leaving the group of engineers here without a job. They determined to build a worthy small wind turbine, and spent several years with grant funding computer designing what became the Iskra AT5-1. It went into small scale production, but the firm was driven by enthusiastic engineers rather than businessmen, hence getting into financial problems and having to get involved with a venture capital group who re-organised it into Evance Wind Turbines. The original founders are all now retired, but keep in contact and advise Britwind in its current iteration.

 

[500e]

Paint will not last any time on leading edge of blades if helicopter ones are anything to go by they use Nickle or SS caps to cut down wear. It eats the alloy without (much higher edge speed though)
There is a Lord glue / filler that wont abraid when used as a filer , will get part No , it is expensive.
The amount of Salt in the air at your location makes it like fine sand paper

 

[Gareth J]

I do like the design of them. We chose it over the slightly larger Proven because I thought it looked better engineered.

Paint will not last any time on leading edge of blades if helicopter ones are anything to go by they use Nickle or SS caps to cut down wear. It eats the alloy without (much higher edge speed though)
There is a Lord glue / filler that wont abraid when used as a filer , will get part No , it is expensive.
The amount of Salt in the air at your location makes it like fine sand paper

Yea, I don't know what the tip speed would be. Not up to helicopter standards but they're up there whirling for a long time. Any coating only has to last a bit more than a year but longer would be better.



Mine stopped again overnight. Replaced the box connector there with wagos but I didn't don't think they were loose.

 

[Gareth J]

Have, this afternoon, changed the sma sb2500s for sb3300s
Quite a bit of size difference. And a bit of a squeeze to get them in.

They're quite a bit less noisy too, which is a bonus. While the 2500s were working, I hope this will result in reliable service that saves me trawling eBay hoovering up cheap but very old sma inverters. This is the last preferred installation setup by britwind, before they moved to a new brand of inverter so, with them being oversized and actively cooled, hopefully they'll be reliable. Very tempting to add a few extra watts in the settings before the FIT expires but hardly worth the risk on a now quite old machine.

 

[Gareth J]

Well, the bloody thing was stopped again this morning. The most obvious reason is that it's simply over speeding and cutting out as it ought to. I'd like to be able to confirm that but the cut outs aren't that often, sometimes it'll run fine for weeks. I could do with a hold peak multimeter that doesn't time out and auto switch off so I can confirm that it does, on occasion, over speed.

 

[Robotstar5]

Look at data loggers, you can download the memory and hopefully the last events will show what caused the shutdown.

 

[GaryS65]

Well, the bloody thing was stopped again this morning. The most obvious reason is that it's simply over speeding and cutting out as it ought to. I'd like to be able to confirm that but the cut outs aren't that often, sometimes it'll run fine for weeks. I could do with a hold peak multimeter that doesn't time out and auto switch off so I can confirm that it does, on occasion, over speed.

Most multimeters that do a peak will auto shut off.

 

[Islander71]

I think the braking system does log basic info. I remember having to use my phone to record the beeps at the bottom of the tower after the brake tripped and sending the recording to Britwind that analysed it to determine it was over-speeding. As I said before though, the easiest way to check when the pitching mechanism is working properly is to let it run free with inverters power cut from mains and see what the voltage is - tapping the lcd on the inverter will cycle through different figures - you want to check what the "uPV" is. It should be between 420-470v. If it is too high, either the blade pitching bearings are notchy, or you need to reduce the torques on the pitching springs. You will need a crows foot socket on the end of a torque wrench to do that after freeing off the "spider" nuts that link all 3 blade pitching together. Mine is set at 39.5Nm which is giving 421v.

 

[Gareth J]

Thanks for the torque setting/voltage. I've only had to alter them once if I recall correctly and I assumed all settings were equal and just turned each one the same amount without measuring torque.

Currently, in free spin, it pitches out to control at about 450V. This figure was mentioned to me as a good control target to go for and it hasn't altered for years so I've left it alone. Have seen a maximum of 460 on occasion and I have written down an absolute recommended maximum of 475. I'll retest it for an extended period next time it's blustery and see if I can see it push higher than 460 at all.

Still not ruling out an irregularly notchy pitch bearing, which would be the obvious cause but hoping to rule a few bit out before I lower it in summer. It could potentially be a dodgy switch in the switch box but seems a bit unlikely given they symptoms. If it's not the pitch bearings, I suspect there must be some water ingress somewhere, it seems very related to rain more than anything else if my observations are right. Thanks again.

It stopped again last night