How does the Chrysler Dual Field Alternator work? What causes it to "turn off"/ "turn on" and go to full load?

The story behind this is that Mancini Racing sold me a "three-wire" alternator that is not a three wire alternator. I am very displeased with them and will not be doing business with them again. I am putting in a new wiring harness and need to make sure that I wire this guy correctly. Thanks.