Re: prony brake

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Steve Conner <steve@xxxxxxxxxxxx>

If you connect enough capacitive load to an induction motor, it will 
self-excite (building up from residual magnetism in the rotor) and 
act as a generator. The output voltage is quite poorly regulated. It 
slips just like an induction motor only backwards: the output 
frequency is slightly lower than the shaft RPM would imply. I don't 
know how something spinning at one frequency can generate a current 
at a different frequency, but it just does.

I believe many of the real cheap and nasty petrol powered generators 
use that design rather than a "proper" synchronous alternator, and I 
know for a fact they use it in low-tech small-scale hydro power 
stations. You can buy an induction generator controller for these, 
that burns off the surplus power in a dump load to keep the frequency 
and voltage within limits. The link below shows a commercial unit but 
you can also obtain (free?) plans and build one yourself if you're interested.

http://www.scs-www.com/Igc.html


Steve Conner
http://www.scopeboy.com/

Tesla list <tesla@xxxxxxxxxx> wrote:
Original poster: "Dmitry (father dest)"

Hallo Sean,

Thursday, March 09, 2006, 1:06:15 AM, you wrote:

i don`t quite understand, how can ordinary induction motor present any
load without external currents in its winding(s)? are you trying to say,
that it acts like a generator even having no permanent magnets? ^_^

> Original poster: "Sean Taylor"

> Another idea for an induction motor . . . If you're spinning fast
> enough (above synchronous speed), you can place a large capactor
> across the terminals and connect various loads. You just have to be
> careful to keep the speed up or the load will d rop considerably.


> On 3/7/06, Tesla list wrote:
> > Original poster: Steve Conner
> >
> > >Use of a generator on bearings works fine and is a lot safer.
> >
> > I've also seen an induction motor used as a brake. You pass DC
> > through the stator windings (any one you like, it doesn't seem to
> > matter much) and it acts as an eddy current brake.

-----
Let the bass kick! =:-D