On Fri, 24 Jun 2005 20:07:44 +0100, pentagrid wrote:

Note - this refers only to SELF EXCITED alternators. The same
machine driven at over synchronous speed and connected to a power grid
works fine as an induction alternator and will feed back to the power
grid the equivalent of it's mechanical input power less its generation
losses. This works well in commercial wind power sytems.

I just had a thought - I'm not that conversant with induction
alternators, but I've heard the term "slip" - which, driving
the shaft mechanically, faster than the synchronous speed, will
generate power - now, my quesion is, if, say, you're on a
windmill, the amount of slip will increase as the RPM increases,
right? Is there some kind of formula or graph - I'd think that
if the "slip" gets up to, like, 90 or 120 degrees, that your
generator efficiency would go back down somewhere, or am I
letting the drugs interfere with my common sense?

Thanks,
Rich