SNS COLLEGE OF ENGINEERING, COIMBATORE.
DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING
EE6401-ELECTRICAL MACHINES-I
Unit.No.:1 (Magnetic Circuits & Magnetic Materials)
Topic. No.: 1
Topic: Introduction to the course
Time Required: 55 Minutes
Syllabus:
UNIT I MAGNETIC CIRCUITS AND MAGNETIC MATERIALS
Magnetic circuits Laws governing magnetic circuits - Flux linkage, Inductance and energy
Statically and Dynamically induced EMF - Torque Properties of magnetic materials, Hysterisis and
Eddy Current losses - AC excitation, introduction to permanent magnets-Transformer as a
magnetically coupled circuit.
UNIT II TRANSFORMERS
Construction principle of operation equivalent circuit parameters phasor diagrams, losses
testing efficiency and voltage regulation-all day efficiency-Sumpners test, per unit representation
inrush current - three phase transformers-connections Scott Connection Phasing of transformer
parallel operation of three phase transformers-auto transformer tap changing transformers-
tertiarywinding.
UNIT III ELECTROMECHANICAL ENERGY CONVERSION AND CONCEPTS IN
ROTATING MACHINES
Energy in magnetic system Field energy and coenergy-force and torque equations singly and
multiply excited magnetic field systems-mmf of distributed windings Winding Inductances-,
magnetic fields in rotating machines rotating mmf waves magnetic saturation and leakage fluxes.
UNIT IV DC GENERATORS
Construction and components of DC Machine Principle of operation - Lap and wave windings-EMF
equations circuit model armature reaction methods of excitation-commutation and interpoles -
compensating winding characteristics of DC generators.
UNIT V DC MOTORS
Principle and operations - types of DC Motors Speed Torque Characteristics of DC Motors-starting
and speed control of DC motors Plugging, dynamic and regenerative braking- testing and efficiency
Retardation test- Swinburnes test and Hopkinsons test - Permanent magnet dc motors(PMDC)-DC
Motor applications.
TEXT BOOKS:
1. Nagrath I. J and Kothari D. P. Electric Machines, Fourth Edition, Tata McGraw Hill
Publishing Company Ltd, 2010.
2. M.N.Bandyopadhyay, Electrical Machines Theory and Practice, PHI Learning PVT
LTD., New Delhi, 2009.
3. Fitzgerald. A.E., Charles Kingsely Jr, Stephen D.Umans, Electric Machinery, Sixth
edition, Tata McGraw Hill Books Company, 2003.
REFERENCES:
1. P. C. Sen., Principles of Electrical Machines and Power Electronics, John Wiley &
Sons, 1997.
2. Syed A. Nasar, Electric Machines and Power Systems: Volume I, Mcgraw-Hill College;
International Edition, January 1995.
3. Deshpande M. V., Electrical Machines PHI Learning Pvt. Ltd., New Delhi, 2011.
4. P.S. Bimbhra, Electrical Machinery, Khanna Publishers, 2003.
5. S.Sarma & K.Pathak Electric Machines, Cengage Learning India (P) Ltd., Delhi,2011.
COURSE OBJECTIVES:
1. To nurture the concepts of magnetic circuits.
2. To enrich the knowledge on transformers.
3. To emphasize the concepts of electromechanical energy conversion devices.
4. To inculcate the knowledge on DC generators.
5. To elucidate about DC motors.
COURSE OUTCOMES: The students will be able to
1. Apply the magnetic materials for Electrical Machines.
2. Execute the operation of transformer.
3. Articulate the design of electromechanical energy conversion devices.
4. Identify the different types of generators and execute them.
5. Categorize the DC motor types and apply for electromechanical energy conversion
applications.
CO-PO & PSO MAPPING:
PO PO PO PO PO PO PO PO PO PO PO PO PSO PSO
1 2 3 4 5 6 7 8 9 10 11 12 1 2
CO1 - 2 3 2 2 - - - - 2 2 - 2 -
CO2 - 2 3 2 2 - - - - 2 2 - 2 -
CO3 - 2 3 2 2 - - - - 2 2 - 2 -
CO4 - 2 3 2 2 - - - - 2 2 - 2 -
CO5 - 2 3 2 2 - - - - 2 2 - 2 -
APPLICATIONS OF ELECTRICAL MACHINES:
1. DC GENERATOR:
Shunt Generators:
in electro plating
for battery recharging
as exciters for AC generators.
Series Generators:
As boosters
As lighting arc lamps
2. DC MOTOR:
Shunt Motor:
Blowers and fans
Centrifugal and reciprocating pumps
Lathe machines
Machine tools
Milling machines
Drilling machines
Series Motor:
Cranes
Hoists & Elevators
Trolleys
Fig.1: Transformer Fig.2: DC motor
