Ammeter pegged...

Lets make sense of the items mentioned; Blue wire, Green Wire, Field.
Field is shorthand for electro-magnetic field.
Blue Wire is the power source for the field and has a branch to tell the voltage regulator whether voltage is going higher or lower than the set point.
Green Wire connects the field to ground through the voltage regulator. If a stronger field is needed, the regulator connects the green wire directly to ground.
If a weaker field is needed, it opens the circuit. There's also an in between connection through some form of resistance.

The rotor windings create the electromagnetic field.
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The Field terminals connect to brushes. (orange arrows)
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