The document provides an overview of DC machines, focusing on the principles and components of motors and generators. It explains the conversion of electrical energy to mechanical energy in motors and mechanical energy to electrical energy in generators, alongside details about their construction and functionality. Key elements discussed include the armature, magnetic field system, and the working rules for motors and generators.

1. Electrical Machines-1
Unit 3: DCMachines
Dr.Mrs. Haripriya H. Kulkarni.

2. Review of previous Lecture
• Transformer-1 phase and 3 phase

3. Learning Objectives
Comparison between Motor and Generator
Study of D.C. Machine
Basics of Machine
Operating principle of Motor and Generator
Different parts and its function

4. Learning Outcomes
Students will be able to :
Compare Motor and Generator
Study of D.C. Machine
Explain basics of Machine
Demonstrate operating principle of Motor and Generator
Different parts and its function

5. Generating and Motoring Action
DIFFERENCE BETWEEN MOTOR AND GENERATOR
+
MOTOR GENERATOR

6. BASIS MOTOR GENERATOR
Function The Motor converts Electrical energy into
Mechanical energy
The Generator converts Mechanical energy to
Electrical Energy
Electricity It uses electricity. It generates electricity
Driven
element
The Shaft of the motor is driven by the
magnetic force developed between
armature and field.
The Shaft is attached to the rotor and is driven
by mechanical force.
Current Current is to be supplied to the armature
of the motor
In the generator current is produced in the
armature windings.
Rule
Followed
Motor follows Fleming·s Left hand rule. GeneratorfollowsFlcming's Right hand rule.
Example An electric car or bike is an example
of electric motor.
Energy in the form of electricity is generated at
the power stations.
Generating and Motoring Action

7. Left Hand-Motor
principle
Right Hand-
Generator principle

8. DC Generator Construction
ADCGenerator isan electrical device which converts mechanical energy intoelectrical energy.
libdkiH:IHI
Itmainlyconsists of three main pa1ts,i.e.magneticfieldsystem,armatm-eandcommutator andbrush gear.
Theother partsofa DCGenerator are magnetic fn1n1eand yoke, pole coreand poleshoes, field orexciting
coils,armaturecore and windings, brushes, end housings, bea,ings andshafts.

9. DC Generator Construction
Arm;nure
CommuUitor
8ru hi,s

10. DCGenerator Construction
-
Field winding/ Pole coils:
They are usually made ofcopper.
Field coils are former wound and placed on each
pole and are connected inseries.
They are wound in such a waythat, when energized,
they form alternate North and South poles.

11. DC Generator Construction
Poleshoes function:
Poles arejoined to the yoke with the help of bolts or welding.
It carries and support the field winding.
To support the filed winding: Pole Core provides this area to
wound thefield winding.
To spread out the flux in air gap:Polecoredirect the magnetic flux
to the air gap, armature, and to the next pole.
0

12. DCGenerator Construction
Armature core/ rotor:
Armature core is the rotor of a de machine.
It iscylintlrical in shape with slots tocarryarmature winding.
11,e armature is built up of thin luminated circular steel disks for reducing eddy current losses.
It may be provided with air ducts for the axialair flow for cooling purposes.
Armature is keyed to theshaft.

13. DC Generator Construction
Armatvr• Windmgl
Armature winding:
Thearmature core slotsare mainly used for holding thearmature winding and itis connected inseries
to parallelfor enhancing the sum of produced current.

14. DCGenerator Construction
Commutator:
The working of thecommutator islikea rectifier forchanging ACvoltage to theDCvoltage within the
armature,winding to across the brushes.
It is designed ,with a copper segment,and eachcopper segment isprotected from eachother,with the
help of mica sheets. It is located on the shaft of the machine.

15. DC Generator Construction
Brushes:
Theelectrical connections can be ensured between the commutator as wellas the external load circuit
with the helpof brushes
Theycollect current from commutator. Made up of carbon or graphite.

16. Student’s Evaluation
Name the parts of D.C.Machine
Flemings left hand rule? Application?
Flemings right hand rule? Application?

17. Assignment
1. Draw constructional diagram of D.C. machine. State functions of different parts along with
the material used.

18. Wrap up
1. Principle of operation of D.C. Machine
2. As a motor, as a generator
3. Different parts of machine
4. Function of each part and construction , significance.