 The field may be "separately excited" by a source of DC, such as a battery, or "self excited" by being connected to the armature of the generator so that the generator also provides the energy required for the field current.A shunt field (and any series resistor used for adjustment) may be directly connected across the armature terminals in parallel with the load.Where the machine has a series compounding winding, the field may be connected at the armature side (short shunt) or load side (long shunt).