Homebrewed Electricity > Hydro

A thought I keep kicking around

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Deveak:
Is it possible to do a direct drive 240 volt AC water wheel and keep it regulated enough that you get 60 hz without electronics or fancy resistor loads?
A waterwheel puts most of its energy in torque and not rpm. So it seems like it would be more stable. Is it possible to have enough torque and gear it up just up above 60hz unloaded that it settles pretty close to it and holds frequency through shear torque? How could it be mechanically and cheaply regulated? I see it costs a pretty penny even for basic resistor regulators. No gen head exists right now so it would have to be an axial PMA. Not sure about the quality of the sine wave though. Pretty much no chance of overspeed though in a larger diameter waterwheel as long as its geared right and the unloaded speed is lower than what the charge controller can handle. Thoughts? Regulation is one thing that keeps me up at night for any pma driven power source. A lot of neat charge controllers exist for batteries but the pma has the risk of burning them up if its not protected with expensive resistive loads machines like the midnite classic clipper. A nice 8-12 foot water wheel seems like an rpm stable power source.

tanner0441:
Hi

I see an 8/12ft water wheel as being quite slow turning and large, where as your 60 Hz PMA would be by comparison quite small and a need to spin up  very fast. Gearing up would give you the speed but a slight variation in speed of the wheel would mean the variation at the PMA would be magnified. You don't actually mention the size of the PMA. I did see a commercial system some years ago and that had a degree of regulation by controlling a bi-pass valve but that was a 30,000 to 50,000 W system.

You could look at the Daf/Ford varimatic drive that has two variable diameter pulleys.

Brian.

mab:
the speed stability of the water wheel is more an illusion that real I think - it's hard to see the difference between slow and a bit slower.

The question is: what do you want to use the power for? Or, how close to 60hz/240v do you want to stay?

I've got a pelton wheel system with and induction motor generator (keep meaning to go PMA but haven't had the time) which unloaded goes to about 1.8 times full load volts, and Hz in a similar ratio, give or take. However, with a simple battery charger load (transformer & rectifier) connected to my main battery bank I can vary direct connected a.c. loads on the generator substantially, and the battery holds the generator volts to within 30%. I.e. the battery and battery dump load regulator effectively regulate the generator. - Hz I'm not so sure about but my direct connected loads are not too picky (even the charger transformer doesn't care as long as you don't exceed the designed Volts/Hz ratio).

If you don't have a battery that wont work for you, but even without active regulation, resistive and transformer loads can be quite tolerant of volts/Hz variation.

Johann:
Use a centrifugal governor. that could apply or release a break or a extra load to speed the wheel  up or to slow it down. It could open or close a adjustable belt pulley to regulate speed like the ones used on riding lawnmowers to regulate driving speeds.
Very old mechanical technology.
See Wikipedia https://en.wikipedia.org/wiki/Centrifugal_governor

Interesting.....yes.
Cheaper.........probably not, unless you have some recycling centers in town to make your own.

On the other hand, why do you need to keep the frequency at 60 hz ?
Most items would run above or below that 60 hz. The only thing would be that some of your clocks would not hold the right time. Europe has 50 hz and you may even use and run some of their 50 hz designed items right now at 60 hz.

joestue:
wouldn't supprise me if a typical waterwheel has a 2 or 3:1 ratio of unloaded to loaded rpm.

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