What must a series generator be classified as?

A series generator is classified as self-excited because it uses its own generated current to produce the magnetic field necessary for operation. In a series generator, the field windings are connected in series with the armature windings, ensuring that the amount of current flowing through the armature also flows through the field windings. This configuration means that as the load increases and the current in the armature increases, the magnetic field strength also increases, allowing the generator to produce more voltage.

The self-excitation process is crucial for the generator's performance, particularly under varying load conditions, as it provides automatic regulation of the output voltage to some extent. This characteristic distinguishes it from other types of excitation methods, such as externally excited systems, where an independent external source provides the excitation current, rather than the generator's own output.