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Re: More three phase fun...

Original poster: Harvey Norris <harvich@xxxxxxxxx>

--- Tesla list <tesla@xxxxxxxxxx> wrote:

> Original poster: "Mike" <mike.marcum@xxxxxxxxxxxx>
> I never actually tried this, but i'm guessing
> probably if you spin it fast
> enough without the bearings giving out. It would
> definitely not be 60hz
> tho. More like a khz, if the core can take it
> without getting hot.
> Mike.
> ----- Original Message ----- From: "Tesla list"
> <tesla@xxxxxxxxxx>
> To: <tesla@xxxxxxxxxx>
> Sent: Wednesday, January 19, 2005 10:36 AM
> Subject: RE: More three phase fun...
> >Original poster: "Steve Conner"
> <steve.conner@xxxxxxxxxxx>
> >
> > >I certainly have
> > >just playing with my AC car alternator over the
> years.
> >
> >Hi Harvey,
> >
> >What's the maximum voltage you can get out of a car
> alternator with the
> >diodes removed? Can it be pushed as far as 200V
> (between phases which would
> >be 120V phase to neutral)
No 35-50 volts is top end operation for this smaller
Delco Remy alternator run at medium rpm ~ 6 inch
pulley from 1725 rpm single phase AC motor establishes
appoximately 480 hz for a 3 pole face field rotor,
which establishes 7 cycles per rotation. Higher rpm
gives higher voltage output for equivalent compared
field amperages, however in the 35-50 volt range
excessive stator core heating occurs, and the higher
the frequency,presumably more the stator core heating
loss. Alternator stators are wired in WYE, so that the
outputs taken as DELTA loads will be the vector sum of
the two 120 degree wye stator coils appearing in
series. This voltage is then 70% higher then the
voltage on a solitary stator winding. A WYE stator
arrangement gives a higher voltage output then a
Delta, which is why they are done that way I suppose.
Thus employing a WYE load on the alternator outputs
would be a WYE to WYE conversion, which is said to
cause balance problems. Typically no 4th return wire
is available for the provision of unbalanced currents
that may occur isn a WYE output.In employing a wye to
delta step up transformer on the alternator stator
lines, I found the output voltage ratios to be
distributed in a 1;2;3 ratio. Thus for equal
distribution of voltages in a three phase step up of
voltage a Delta primary is advised.