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.
The Field terminals connect to brushes. (orange arrows)