Series-Wound DC Generators

When the field winding of a DC generator is connected in series with the armature, the generator is called a series-wound generator (Figure).

The excitation current in a series-wound generator is the same as the current the generator delivers to the load. The excitation current is also small if the load has a high resistance and only draws a small amount of current.  Thus, the magnetic field of the series field winding is weak are making the produced voltage low.

                                                       Figure: Series-Wound DC Generator

Conversely, the excitation current is also high if the load draws a large current. Thus, the magnetic field of the series field winding is extremely strong, and the produced voltage is high.

                                               Figure: Output Voltage-vs-Load Current for Series-Wound