Construction and parts of dc motor or dc generator

construction of dc generator and dc motor is similar . A dc motor can be used as dc generator without any constructional changes or vice versa.There are some main part such as  Armature, Rotor, Stator, Field, commutator, brush and yoke.

Construction of dc machine
Construction of dc generator
Construction of dc motor

Construction and parts of dc motor or dc generator:

1. Armature
2. Rotor
3. Stator
4. Field
5. commutator
6. brush

fig.1 DC Generator construction

Armature:

Armature is rotating part of machine, It is conductor coil which cuts magnetic flux of magnet and generate electrical energy at output terminal
The purpose of the armature is to provide the energy conversion in a DC machine (refer to Figure ).

In a DC generator, the armature is rotated by an external mechanical force, such as a steam turbine and wind turbine . This rotation induces a voltage ( as per faraday law) and current flow in the armature. Thus, the armature converts mechanical energy to electrical energy.

In a DC motor, the armature receives voltage from an outside electrical source and converts electrical energy into mechanical energy in the form of torque.

Rotor:

Rotor is moving part.
The purpose of the rotor is to provide the rotating element in a DC machine (refer to Figure 2). In a DC generator, the rotor is the component that is rotated by an external force. In a DC motor, the rotor is the component that turns a piece of equipment. In both types of DC machines, the rotor is the armature.

Stator:

stator is fixed part.
The stator is the part of a motor or generator that is stationary (refer to Figure 1). In DC machines, the purpose of the stator is to provide the magnetic field. The stator in Figure 1 is provided by permanent magnet (generally electromagnets are used).

click to read 

1) Working principle of dc generator.

2) Working principle of dc motor.

Field:

The purpose of the field (winding) in a DC machine is to provide a magnetic field for producing either a voltage (generator) or a torque (motor) (refer to Figure 1). The field in a DC machine is
produced by either a permanent magnet or an electromagnet. Normally, electromagnets are used
because they have an increased magnetic strength, and the magnetic strength is more easily varied
using external devices. In Figure 2, the field is provided by the stator.

Yoke:
Yoke is frame and outer covering body  made up of iron metal.

Comutator:

AC to DC Voltage converter.
The commutator converts the AC voltage generated in the rotating loop(ARMATURE) into a DC voltage. It also serves as a means of connecting the brushes to the rotating loop(ARMATURE).
In a simple one-loop generator, the commutator is made up of two semi-cylindrical pieces of a smooth conducting material, usually copper, separated by an insulating material, as shown in below Figure . Each half of the commutator segments is permanently attached to one end of the rotating loop(ARMATURE), and the commutator rotates with the loop(ARMATURE).

commutator with carbon brush