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1. ELECTRICAL MACHINES
INSTRUMENTATION &
CONTROL DEPT
D.C GENERATOR
PREPARED BY
KETAN NAYAK (140413117005)
ASHISH PATIL (140413117009)

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

3. 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.

4. PRINCIPLE OF OPERATION
• In 1831, Michael Faraday, an English physicist gave
one of the most basic laws of electromagnetism
called Faraday's law of electromagnetic induction.

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

6. 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.

7. 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.

8. 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.

9. 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.

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

11. 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.

12. WORKING of DC GENERATOR

13. • 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.

14. • 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.

15. 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

17. CLASSIFICATION

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

19. • 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