http://en.wikipedia.org/wiki/Shunt_generator describes the differences between a series wound generator and a shunt wound generator.
The Model A generator is shunt wound, but of special kind in that the voltage impressed across the field is a function of the position of the 3rd brush. Thus at a constant rpm, the operator can adust the voltage of the field, and thereby adjust the current and voltage both of the output.
Quoting the article above:
Quote:
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Current in the field windings of a shunt-wound generator is (approximately) independent of the load current, because currents in parallel branches are independent of each other. Since field current, and therefore field strength, is not affected by load current, the output voltage remains more nearly constant than does the output voltage of the series-wound generator.
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No stealing from total current by the field. It is a separate circuit. It happens to be variable at the behest of the 3rd brush (or a voltage regulator should that be the adjustor.)
We can throw the additional variable of engine/generator speed at this as well, but it only serves to provide a different starting point for the movement of that third brush.
I will be willing to simply call it a draw at this point. We cyberly shake hands and call our differences "interesting."
This so we can better help the guy going forward. I think the ball is in his court now.
Joe K