DC motors for wind power

I saw a programme on the TV a while back, where a fully submerged vertical turbine, had been placed in a river here in the UK, that had a substantial tidal flow. The flow rate of the water first in one direction, and then in the other as the the tide turned, was remarkably constant, and allowed the thing to generate failrly significant amounts of electricity, more or less continuously. I think it was part of an experiment to see if this was potentially a good way to harness tidal energy.

Arfa

Agreed on that !

Arfa

A generator with a commutator i.e. a car dynamo from days of yore, *does* produce DC, and does it without diodes, courtesy of the switching action of that commutator. I can't imagine how you've never seen one, as back in the fifties and sixties - that is fifty years ago - that's about the only type of generator that was fitted to car engines ...

Arfa

Read the previous response, where he says that the commutator does not switch (windings).

OK. I see what you're getting at. There did seem to be a couple of statements slightly at odds with one another, one of which you didn't include. However, the two lines about his VW generator producing DC without diodes which you did include, is a perfectly reasonable statement, and your response to it implied (to me at least) that it is not ... Maybe just one of those 'linguistic' things ... d;~}

Arfa

Backwards. To some people, everything is a problem.

Thanks. I didn't know about that one. The usual problem with submerged turbines in rivers is keeping rubbish, fish, swimmers, critters, and debris out of the turbines. I don't see any filters, sediment traps, diverters, grills, etc. I prefer to filet my fish myself, not to have it done by a turbine. Mechanical feathering for high flow flood conditions also needs to be addressed. Despite these problems, hydro has some huge advantages. Of all the common technologies, it's the cheapest and also the cleanest.

Last year i trashed a big comp tape drive, so i know that feeling. But one would not get me far anyway, i need quite a few.

Bart

You need to read the context of the posts. Mr Liebermann originally didn't realise the commuter in a dynamo does the same job as diodes in an alternator.

--
*Why is the man who invests all your money called a broker?

    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

I don't think it was Jeff who said that ... ?? Mr Nebenzahl maybe ? The post is getting a little scruffy in construction here and there. Anyway, if replying to specific comments, these should still be included or properly referenced in the reply. You can't rely on people remembering things that have been said further up the post, particularly when some responses may not even appear to some people due to filters that they have in place for all of the crap that finds its way onto here now. Whatever, the couple of lines that Sjourke did see fit to copy to his response, were valid, and his comment seemed to laugh at them as being wrong, at least to me. Anyway, I don't wish to argue with either of you. I've got more important things to do. If I misunderstood anybody's responses or posts, then I apologise.

Arfa

A thousand apologies to Mr Liebermann - you're right. Put it down to a senior moment. I'm getting rather too many of those recently. ;-(

It does get a problem when trying not to just hit reply and quote and fill the group with unnecessary data. I think any post you have to scroll down is too long. ;-)

--
*\'ome is where you \'ang your @ *

    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

I know a farmer who charges his fence charger with a sun panel. Would be cool to build a waterwheel type charger since he does have a little stream coming out of a PVC pipe from his pond. The pond has a spring at one end and always has a decent output. He sometimes has to use a generator and charger especially in the winter months when sunlight is scarce. He doesn't want to put up 5 poles to the pasture to provide AC power to a fence charger but the pond is very near and the stream runs right through the pasture. Would be a good little project to design a waterfall turbine at the pipe outlet.

I guess it's a 'thinking out of the box' thing. Seperates the droids from the go getters.

That wasn't me. If it had been me, I would have:

1. Insulted the original author.
2. Complained about the lack of editing quotes, excessive brevity, lack of information, lack of writing skills, excessive cross posting, improper formatting, or various combinations.
3. Explained exactly how things work, even if I were wrong.
4. Supplied URL's to sites that agree with my conjecture.
5. Supplied irrelevant but interesting URL's on related subjects, such as one does not need a commutator or diodes to generate DC:

1. Supplied a marginally relevant and occasionally entertaining story from my checkered past[1].

1. Supplied a contorted footnote vainly attempting to either remain on topic, or somehow partially connect my statements with sci.electronics.repair.

Since the original allegation does not in any way resemble my standard style as itemized above, it obviously was not my posting.

[1] Expanding on my college wind generator project.... I went to Cal Poly Pomona, which believes in "Learn by Doing" which I ammended into "Learn by Destroying". My degree was in "electrical and electronic engineering" which at the time involved several classes in motors. One class was divided into random groups of 4 students. The instructor then asked "Who has an old automobile generator laying around"? Like a complete idiot, I raised my hand and our groups was instantly sentenced to 3 months of hard labour building a wind powered generator around it. It was suppose to be the reference or worst case design, as everyone else was allowed to use alternators or PM motors. Ours worked, sorta. To get enough wind, it was installed in the bed of a pickup truck, and driven at unsafe speeds down the freeway. A traffic ticket was avoided by promising never to do it again. That worked for our group, but failed miserably when some of the other groups had the same idea. Another lesson learned was that plywood propellers tend to self destruct at about 50 mph.

"The basic assumption of the repair business is that previously it actually worked properly. Anything else is re-design or engineering". (Me after fighting a losing with some piece of badly designed junk).

--
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

Indeed - I'm sorry. I apologised in a later post.

--
*I have a degree in liberal arts -- do you want fries with that

    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

You can find them on Sam's Club website 400W for $600

here:

and better i think:

Alain

"Bart Bervoets" a écrit dans le message de news:

4a6b4ffa$0$2850$ snipped-for-privacy@news.skynet.be...

Never tried it, but the brushless outrunners used e.g. in model RC planes might work, specially high KV units (hi torque, low rpm). Basically these are 3 phase stepping motors, but with some rectifying it could owrk. And they are getting rather cheap too.