The document provides an overview of D.C. machines, specifically D.C. generators, outlining their principles, construction, working, and applications. It describes important components such as the yoke, poles, field winding, armature, and commutator, explaining their functions in the generation of D.C. electrical energy. Additionally, it classifies various types of generators and highlights practical applications like battery charging and electric arc welding.

1. Module 3
DC MACHINES
Prepared by
Mr V L Jiddi
Asst.Prof, Dept of EEE
BLDEACET Vijayapura

2. ELECTRICAL MACHINES
D.C GENERATOR

3. INDEX
S.r no Topic Name
1 INTRODUCTION
2 PRINCIPLE OF OPERATION
3 CONSTRUCTION
4 WORKING
5 CLASSIFICATION
6 APPLICATIONS

4. INTRODUCTION
• The Device which Converts the Mechanical Energy into Electrical
Energy is called Generator.
• There are Two types of Generators
1. D.C Generator:- The Generator which converts the Mechanical Energy
into D.C Form of Electrical Energy is called D.C Generator.
2. A.C Generator:- The Generator which converts the Mechanical Energy
into A.C Form of Electrical Energy is called A.C Generator.
• Both of the Generator Works on the Principle of Faraday’s Law of
Electromagnetic Induction.

9. CONSTRUCTION
• Important Parts of D.C Generator
1. YOKE
2. POLES
3. FIELD WINDING
4. ARMATURE
5. COMMUTATOR,BRUSHES and GEAR
6. BEARINGS

10. YOKE
• Yoke is also called as frame. It provides
protection to the rotating and other
parts of the machine from moisture, dust
etc.
• Yoke is an iron body which provides the
path for flux
• It provides the mechanical support for
the poles.
• Materials used for yoke are cast iron,
silicon steel, cast steel, rolled steel etc.

11. POLE
• Pole produce the magnetic flux
when the field winding is excited.
• Materials used for Pole is cast steel
or cast iron.
• Pole is a Part on Which Field
Winding is Wound Over.

12. FIELD WINDING
• The field winding is also called as
exciting winding.
• Current is passed through the field
winding in a specific direction ,to
magnetize the pole.
• The metal is used for the field
conductor is copper.

13. ARMATURE CORE
•All these slots are parallel to the
shaft axis.
•Armature conductor are placed in
these slots.
•Armature core provides a low
reluctance path to the flux produced
by the field winding.
•Cast steel or cast iron are used for
the armature core.

14. COMMUTATOR
• generated internally in a
D.C. voltage .
• It collects the current from
the armature conductors
and passes it to the external
load via brush.
• The commutator
the alternating
converts
emf

15. ROTOR
• The Rotor is the moving part of a
D.C. generator.
• The rotor rotates because the
wires and magnetic field of the
motor are arranged so that a
torque is developed about the
rotor’s axis.

16. WORKING of DC GENERATOR

17. • The Dc Generator Converts Mechanical Energy into
Electrical Energy.
• In this DC Generator the Single Turn Alternator is used.
• The Coil can Rotate in Clockwise or Anticlockwise
Direction.
• The Commutator Brush is Connected to the Coil.
• Commutator is Divided into Two Parts A and B.
• The Coil is Suspended between the Field Poles.
• The Coil is Given the Mechanical Energy which Results in
the Rotation of it.
• As the Commutator Segments A&B is Connected with
Conducting Coil ab and cd Respectively they Rotate
Together.
• Due to Which the Flux is Produced Resulting in the
Generation of Electric Current.

18. • As the Commutator has the Property of Converting
the Bidirectional Emf(AC) into Unidirectional Emf
(DC) .
• The DC Current is Generated by the DC Generator.
• Which can Directly Used by Connecting the Output
across the Load or it Can be stored inatteries and Can
be used Later on.

19. GENERATION OF AC
VOLTAGE
• As Shown in Fig the Coil is in Rotating Form.
• The EMF is Generated by Rotation of Coil.
• In this Fig A,B,C and D is used to Describe the
Position of the Coil.
• When the Coil is stationary the EMF
Generated is Null.
• When the Coil Rotates at 90 Degree as Shown
in Fig B.The Flux is Generated resulting in the
AC Voltage at Output.
• When the Coil Reaches at C the Half Cycle of
the Rotation is Complete .
• When the Coil Rotates Further another Half
Cycle of Sine wave is Generated .
• The Efficiency of the DC Generator can be
Increased by Combining Two or More Number
of Coils at Same Time .
• Which Will Result in Attaining 360 Degrees at
only One Rotation of the Coil

21. CLASSIFICATION

22. APPLICATIONS
• Shunt generator:
Lighting loads
Battery charging
• Series generator:
For the arc lamps
As constant current generator
As boosters on D.C. generator

23. • Separately Exicted generator:
The application of these generator have
limitations , because they need a separate excitation for
the field winding. Some of the application are electro-
refining of materials or electro-plating
• Cumulative compound
generator: Used for
domestic lighting
For energy transmission over a long distance.
• Differential compound generator:
• Its important application is electric arc welding