Workshop in Austria

In Vienna, In German language, With Jonathan Schreiber on 12-14th October and 19-21 October
Cost 375€

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Tripalium celebrate ten years of turbine building



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Workshops in Argentina

Here is the latest wind turbine workshop by 500rpm in Argentina.

Evento que se celebrará a la hora, en la fecha y ubicación siguientes:

Sábado, 25 de agosto de 2018 a las 09:00

– hasta –

Domingo, 26 de agosto de 2018 a las 18:00 (ART)

Maestro M. Lopez esquina Cruz Roja, AVEIT, Córdoba capital

Maestro M. Lopez esquina Cruz Roja


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My windmill and my house on drone video

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Powerspout documents free to download

Much of my time these days is spent helping people with microhydro projects.  I love it.  As well as answering emails and phone-calls, I’ve been spending a lot of time helping with the PowerSpout free document library.

Click the links to view the documents.  Then click the download symbol to a the top of the screen to download them.

When planning your system, these ones could help you:

You can estimate your site’s generation potential, and even design the whole system painlessly using the online Advanced Calculator Tool. To get the best out of it please read the Hydro design and calculator manual first.

Lots of guides to off-grid system design:

There are lots more documents in the Index.  I hope you find them useful. If you aren’t sure about anything just drop me an email and I will help.

Posted in Books, my own projects, PowerSpout hydro turbines | 1 Comment

More free design documents from Adriaan Kragten

Adriaan writes

Dear Hugh

I am 71 years old now and in December 2017 I have ended the commercial activities for my engineering office Kragten Design. But I am still active and my website: will be maintained as long as possible. In the first half year of 2018 I have written five new free public KD-reports. Four of these reports give rotor calculations. At the menu “News” on my website you find a short description of the content of each report. At the top of the menu “KD-reports” there is the folder: “List free public KD-reports” and the folder “Sequence of KD-reports for self-study” which, I think, will be of great help for someone who wants to design a wind turbine.

Adriaan Kragten

Thanks Adriaan.  This is a wonderful resource for students of wind turbine design.  Here is a chart from KD35 showing the relationship between conversion “efficiency” and drag/lift ratio, over a range of tip speed ratios:

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Off-grid house for sale

My friend Jamie is moving on from his off-grid house so I am posting details. This house is powered by a PowerSpout turbine and a PV array.

Knoydart, Mallaig, PH41 4PL
Offers Over

“No 2 Doune is in a small cluster of houses, one of four private dwellings, overlooking Doune Bay on the Knoydart peninsula. The house is in a spectacular setting, positioned against the hillside and with stunning views over the sheltered bay and the Sound of Sleat to Skye. ” More here.

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6-day-workshop for a 2F HP Turbine from 23rd to 38th June in Lörrach, Germany

ERNI e.V., together with the Dieter-Kaltenbach-Stiftung conduct a 6-day-workshop for a 2F HP Turbine from 23rd to 38th June in Lörrach, Germany.

Application is available here:

Costs: 400€ for all 6 days

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wire size and current

I got an email question today and it seems important enough to answer with a new post.  Here is the question “How many amp of 14,15,17,18 and 20 awg wire for wind turbine. Can you give me any chart? Please!!!!! ”

If you are winding a stator according to my style – about 13mm thick coils with some glass cloth on the faces and plenty of wind blowing past it – then my rule of thumb is about 6A RMS current per sqmm of wire cross section. If the stator is star/wye connected, with a single wire in hand and all coils in series then the DC output will be about 22% higher than the RMS AC current.

The relationship between AC current in each phase and the DC output of the rectifier depends on the waveform. But the simplest way to think of it is to say that each wire carries the full DC current for 2/3 of the time, and is resting for 1/3 of the time. The result is that the rms AC current in each wire is root(2/3) = 0.82 times the DC current. In reality the wires share current some of the time, so the % is very slightly lower in relation to the DC.  But this 0.82 is the worst case, and it is very close to the reality usually.
So maximum DC current should be about 1.22 x maximum allowed AC current as in the table.

So here is my answer:

It’s OK if the current surges way above this value in a gust, but this is the maximum sustained current I would design for, as a safe target. Your furling tail should prevent the machine from kicking out more than this on a continuous basis. If output is higher then make the tail lighter to reduce amps.

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my 1998 blade design notes translated into Russian :-)

I used to teach blade design.  I went to Wales to learn (more) about windpower on a course (in about 1989), but the guys there made me teach the session on blade design.  They just announced that I would do that class and sat down. That was scary.

I kept on going back down there and helping with the courses for years, and so ten years or so later my blade design lecture got to be recorded in a PDF (which was a pretty novel thing at the time).  You can find this PDF on my old website here.

Today I found out that the notes have been translated into Russian.  That’s cool 🙂  I love the Russian language although I have not tried to understand it since I was at school.  I am glad nobody is asking me to teach blade design in Russian(!), but if they did I would at least have the notes to make a powerpoint for the class.

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