Hi BobG,
I asked questions about the issue of inductance and learned that it's much more complicated than I previously thought:
http://www.fieldlines.com/story/2006/7/4/425/44513
I obviously wasn't asking about the same thing, but the response was so informative, that I keep that thread printed out and in a binder with other "useful thoughts" that I've picked up along the way.
If you were to draw out a diagram of one phase of, say, a 4-pole stator, you would have a pattern like a four-leaf clover. If you wound a phase with two separate lengths of wire, one going clockwise, the other counter-clockwise, then all that would achieve is current flowing clockwise in one, and counter-clockwise in the other. The reversal of the winding direction and the reversal of the current direction makes two negatives multiply, leaving you with the same positive result.
Anyway, The field lines must be viewed as a complete "circuit", and trying to isolate one coil and the field through it gives nonsense answers. This isn't always what's dominating in iron-cored generators, there's the interaction between the rotor and stator, eddy currents, hysteresis; I still can't list them all.
Steven Fahey
