Construction and Working of DC Machines

DC Machines Construction and Working

The DC machine comprises the construction of both Generator and Motor. The mode of working only decides whether DC generator or a DC motor. In this post, you will be getting to know “how dc machines work?” and also construction and working of DC machines.

Let us see the construction of DC machine in detail.


The Yoke is the Outermost part of the machine which comprises of all other utilities.

The function of a Yoke

The main function of the yoke is to protect the machine dust, moisture and some of the gases like Sulphur dioxide and acidic fumes.

Yoke provides the mechanical support to the machine.

The yoke is a part of a magnetic circuit and it provides a low reluctance path for the magnetic flux. A low reluctance path is important to avoid the wastage of power to provide the same flux.

Choice of material

It should be of magnetic material in order to provide low reluctance path. The first preference would be of cast iron, for larger machines rolled steel, cast steel or silicon steel can be used.


Poles are divided into pole core and pole shoe.

Function of poles

The pole core contains a field winding which produces flux when energized.

Choice of material

It is made up of magnetic materials like cast iron or cast steel. The shape and size are more important for its operation.

Field Winding

The Field winding is wound on a pole core in a respective sequence.

The function of Field Winding

It helps in producing the magnetic field that is exciting the pole as an electromagnet. It is also called a field winding or exciting winding.

Choice of material

It carries current so metals (conducting) like aluminium or copper can be used. Copper can bend easily while compared to aluminium So the copper is preferred more.


The Armature is classified into armature core and armature winding.

Armature Core

The Armature core holds the cylindrical shape which is mounted on the shaft. It consists of slots and air ducts, which enhances the air flow and serves as a cooling purpose.

Functions of the Armature Core

The Armature Windings are wounded on the armature core.

It provides a path of low reluctance to the magnetic flux produced by the field winding.

Choice of material

It is usually made of magnetic materials like cast steel or cast iron to provide low reluctance flux. To minimize the eddy current loss, it is usually laminated.

Armature Winding

The Armatures windings mean the interconnection of Armature Conductors.

The function of Armature Winding

Emf is produced in armature winding, in case of a generator.

The current flow through the armature winding in case of motors.

To connect internal circuit with an external circuit.

Choice of material

The copper is used as an armature winding. The armature slot holds the conductor lined through an insulating material.


The emf induced in the armature winding is alternating so for a DC generator, it should be rectified to get DC output, which is done by the commutator.

Function of Commutator

In case of a generator, to convert Alternating emf into unidirectional DC emf.

In case of motors, to provide unidirectional torque.

Choice of material

The commutator is also made up copper. It is cylindrical in shape. It consists of a commutator segment which is insulated from each other by a thin layer of mica.


Function of Brushes

To connect internal circuit with the external circuit.

Choice of material

The brushes are usually made of soft materials like carbon.



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