Water pump motor for wind turbine project?

[Jules Richardson]

For sure - but I doubt that Volvo's the only way to go; I'd suggest to anyone embarking on such a project to scope out their local yards (if such a thing's allowed any more - I know my local one don't allow people to just wander in to see what they have) as there are probably all sorts of things that might be suitable.

(I wonder how suitable a second bearing assembly, mounted vertically, would be for providing the swivel functionality, given that they're designed to operate with the weight of a car on them? It'd be relatively easy to pull both bearing assemblies from a junk car, anyway)

Have a URL handy? If not, I'll take a look around... sounds interesting.

It certainly seemed a bit 'odd' given the kind of shape I'd expect for a [wind] turbine blade.

Thankfully I have a barn here that's about 40' to the roof-line, so I'd "just" mount any turbine that I tried to build up there, I think; it wouldn't need much of a pole beyond what was necessary for the blades to clear the ridge. For others though, yes I can appreciate that the supporting structure is a major part of the problem.

cheers

Jules

[The Natural Philosopher]

Er, absolutely NOT.

you can get motors up to 10KW rating, and capable of generating useful power down to a few hundred RPM.

Do you really think a motor designed to DRIVE a 30" prop on a model at over 70mph, wont be big enough to handle the output of such a prop at 30mph?

's a 2-3bhp motor. Starter motor sort of power.

You can trade voltage for current by rewinding as well, if you want. Its not very hard.

I doubt whether a 36" prop in a 30mph breeze would be capable of much over a Kw at best.

Probably about 1000 RPM.

Using a motor designed for several KW at 40-50v and 4-5000 RPM would get you about 10v and about 50-70A potential output.

Gear it, and you might get a bit more, but it gets complicated.

Easier to simply use a BIG motor.

[The Natural Philosopher]

Tapered rollers at each end of a tube would be find, both for lateral and vertical loads.

Slip rings to get power out are perhaps a worse problem.

One way might be to use a bevel gear to take a vertical shaft down to a statically mounted motor..step up would also net a decent RPM for the genny bit.

As you are US based, you might care to gawp at this site

have used them from the UK but what I thought I would pay doubled by the time they had used the most expensive courier possible, and involved me in a shitload of customs forms and extra charges.

[AL_n]

The Natural Philosopher wrote in news:i8vbo5$7ll$1 @news.albasani.net:

And long may that state of affairs continue. ;-)

Why did you opt for an outrunner motor, in particular?

Al

[AL_n]

The Natural Philosopher wrote in news:i8vd19$9kb$ [e-mail]:

Would a car starter motor do the job? If not, and I end up buying one of these model aircraft motors, perhaps I can even get one with bolt holes for a 3-blade prop. That would save a lot of hassle.

In case it's of interest, I found this spec sheet for a commercially produced domestiv wind turbine with a 1.19m dia 3-blade rotor (somewhat smaller than mine):

perhaps with my larger diameter rotor, I could hope to achieve at least the same output with a suitable generator.

Al

[Jules Richardson]

Hmm, I suppose on modern vehicles there must be some form of hole through the bearing assembly for things like tyre pressure sensors? I wonder if light-weight trailer bearing assemblies might not have a hollow path through them, too.

Yeah, that had crossed my mind, too. Simplifies the power transmission, but I don't like the extra frictional loss involved (unless, like you say, there's a need to change drive ratios anyway)

I'm lucky in that my local farm supply place is a treasure-trove of bearings, linkages, pulleys etc. as spare parts, so I can just wander in and take my time looking at this stuff on the shelves.

cheers

Jules

[Andy Burns]

I thought they were either wireless, or worked on wheel speed differences measured by the ABS sensors?

[The Natural Philosopher]

More poles = lower KV for a given size = more volts per RPM.

Also cheaper and a piece of piss to rewind. More turns of thinner wire nets more volts at less amps.

Rewindables though..go to China for CHHEEPP

Like this monster

'd aim for about 50-100 RPM/volt, and no more than 10-15A max current.

These things are not great quality wise. Lots of people reglue the magnets, replace the bearings and rewind. But the magnets are good quality neodymium. Ad at low RPM the stators are not too bad either. Dont work well at high switching due to eddy current looses, but fine at low frequencies.

At low RPM they wont do the goods that they are rated for, but they do work. No need to reglue magets for low RPM use, but a rewind to get usable volts out of very low RPM is no bad thing.

We have run 14-20v motors on 7v to swing large scale propellors SLOW. they work OK, but the power per lb of motor is not that great.

Gears work better, but it all gets complicated.

I do think Id e after a 2:1 bevel drive off the blades though, and a vertical shaft down to the motor.

That means there isn't so much exposed to the weather. And a simple weathervane should keep it pointed into wind.

[The Natural Philosopher]

yeah. I think you might see peaks up around 500-800W. That's roughly what it takes to swing a prop like that at a couple of thousand RPM in static conditions, so the reverse should apply.

Id really go for the aircraft motors because they are actually efficient with decent magnets.

And relatively cheap.

BUT there is still a lot of electronics to regulate and upconvert the voltage, and a lot of bearing/geabox s**te to add.

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "AL_n" saying something like:

Well, used alts are dirt cheap and so are rare earth PMs, so you go for it. :)

[AL_n]

The Natural Philosopher wrote in news:i8vo4f$qo5$1 @news.albasani.net:

$1

Thanks for the guidance. I looked on eBay.uk but only tiny examples seem to be appearing at the moment - even those located in China.

Thanks for your input. Yes - keeping it pointed into the wind seems easy enough, using bits of glue-fit waste pipe and sheet aluminium/perspex/etc.

Al

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember Andy Dingley saying something like:

Or ditch the reg/rec and take the output as raw 3ph 120V (ish) AC and transform it at the bottom of the pole/in the shed/wherever for more efficient transfer to where it's needed.

[Jules Richardson]

Hopefully someone will be along to say! I did always wonder. Hadn't though of doing it via speed sensors, but I suppose that would be quite sensible, assuming it was averaged over a period, and/or readings only taken when the vehicle was travelling in a straight line etc.

Our van actually throws up a warning even though the tyres are OK, so knowing how the system typically works might motivate me to go and investigate :-)

[Andy Dingley]

No - they won't work at slow enough rpm. You're actually better off with a car alternator.

Wind turbines aren't about generating the most power possible, they're about increasingthe number of days when you get to do any generation at all. You need a turbine and generator that picks up at low speeds - it'll give you far more energy over a year than using a bigger generator does.

[The Natural Philosopher]

yes they will. car alternator barely gets out of bed before 1500 RPM.

That's purely a winding matter ad the number of poles you have.

[<me9]

Mine uses the ABS sensors. Isn't that the norm?

[Andy Dingley]

That depends on the regulator, and on the supply to it. Most will generate down to 500rpm as standard, and they'll go lower if you play with the regulator.

Where they don't usually do this on cars, that's a bootstrapping behaviour. Once spun at higher speed, their output becomes enough that they "turn on" and latch, and will continue generating down to much lower speeds. Again, you can address that through the regulator.

Yes, number of poles. High-speed aircraft motors don't have enough.

IIf I have to mess about with rewinding, then I'm going to do so with a direct-drive pancake generator, a la Piggott, and do it right.

[Andy Dingley]

Something needs to excite the rotor windings. When an induction motor is used as a motor, relative slip does this (the well-known squirrel cage motor).

If you want to use an AC motor as a generator, you need to supply an excitation current to the motor, through slip rings and a rotor winding (not just a squirrel cage, as the low impedance isn't conducive to operation with brushes). This is how large AC generators operate.

What you describe here is a super-synchronous generator. Yes, energy from the mechanical drive will end up as electrical power. However you're also having to drive the induction motor with an applied voltage, and that's even more than would normally be supplied for rotor excitation. It's no practical way to make a generator.

[Andy Dingley]

So what you're saying is that I can use a squirrel cage motor as a generator for a wind turbine, I merely have to supply excitation current to it with two steam turbines and a diesel engine?

I think I'll pass on that.