single phase motor as grid connected dc to ac rotory converter

[Justme]

I have planned to build a nano hydro turbine, having availble 1 litre constant flow at 3 metre head. And so back to this problem of getting a single phase motor to output into the mains.

Assuming thats 1L per second & that my calcs are correct that is just under 30watts.

power = head X flow X gravity (9.81)

Does not sound like much but would provide nearly 25% of our total daily needs.
Would be a big help in winter.


But I would guess that the systems efficiency would not be 100% so actual made elec would be nearer 15 watts.

[odbob]

Justme, This is the thing, neither the rotory converter or the hydro sound much until you compare to a years output, having said that, I'm still struggling with the initial prob of extracting power from the ac motor and that's where I was looking to you Guys for the answer, My single phase motor must be of a resistance start, no capacitor, Maybe the probs in the windings, maybe excitation from the mains doesn't work in the same way as with 3 phase?

[johnrae]

If it's only low wattage and has no capacitor then it is probably a shaded pole motor.  If it is, I think your chances of getting it to generate are slim as the shaded pole is designed with inbuilt inefficiencies which are necessary to produce rotation.

You'd be better off getting hold of a larger capacitor start type motor (say 1/2 HP) and use the start windings as a means of excitation.  However at run speed the centrifugal switch - if there is one - will be open so you will need to "shorten" this out.  Also the start winding is not intended to be permanently energised so you will need to introduce a load limiter.  I'd suggest you fit a pair of wires across the centrifugal switch, bring these out through the terminal housing and then connect these to a lamp socket.  Fit a bulb in the socket and this will serve the dual purpose of acting as a winding current limiter and take care of the opened switch.  What size bulb ?  who knows but I'd try a 60watt as a starting pointy.  It MUST be an incandescent type, not a modern energy saver.

[biff]

hi odbob,
          have a squint at outtasight,s posts on "cobbled together solar in w,sussex" there has gotta be something there to intrest you,
                                                                                                                                                     biff

[odbob]

Johnrae, now, this is probably the answer as to why I can't get an output from it, not an answer I had hoped for but so beit
More than likely is a shaded pole as you call it, not having worked with such tiny motors before,would you mind explaining further, why it should differ so much from a normal squirrel cage motor, and why you feel that it won't output?

Biff, thanks, will look at his posts

[wyleu]

Shaded Pole motors
AC Motors

[biff]

exellent link wyleu,
               biff

[odbob]

Chris, thanks for the link, I see now the difference, shaded pole motors are easily recognised, I have a number of these and didn't know that was the name given.
However, I can now say that the motor that I am trying to output, has all the design features of a tiny squirrel cage motor, which I am pleased about.
and so still experimenting.

Thanks all that gave constructive comments