Field
The connections are labled field because when electricity flows through the rotor windings it creates an electromagnetic field.
The terminals connect to cabon brush that contact the slip ring.
View attachment 1715573616
When the voltage is at or near 14 Volts, the regulator reduces or cuts off the flow of current to the rotor.
Two insulated field terminals
With a positive controlling regulator, like the one you bought, the second terminal needs to be grounded.
Something like this will do.
View attachment 1715573617
That makes it the same as alternator with only one brush in an insulated holder.
View attachment 1715573618
That's why the phrase 'two field' or 'dual field' is really misleading. In both types there's only one rotor and only one magnetic field created when power flows through them. The difference is the number of terminals that need to be wired.
