Types of DC machines:

Types of dc generators

The generators are classified according to their field excitation. The types are

(a) Separately-excited dc generator:

In Separately excited dc generator, field magnets are energized by the external source of dc current.

(b) Self-excited dc generator:

In Self-excited dc generator, the current energizes field magnets produced by the generators themselves. This type of generators further classified into

(1) Shunt wound:

The field windings are connected across or in parallel with the armature, so that field windings have full voltage of the generator.

(2)Series wound:

In this type, field windings are joined in series with the armature, so that they are carrying the full load current. The series field windings are made of few turns of thick wire or strips.

(3)Compound wound:

It is a combination of a few series and few shunt windings. It is further divided into two types. They are long-shunt and short shunt. The shunt field is stronger than the series field. When series field aids the shunt field, then the generator is called as commutatively compounded. When series field opposes the shunt field, then the generator is said to be differentially compounded.

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