18EE44 Electric Motors syllabus for EE

DC Motors:

Classification, Back emf, Torque equation, and significance of back emf, Characteristics of shunt, series & compound motors. Speed control of shunt, series and compound motors. Application of motors. DC motor starters – 3 point and 4 point.

Losses and Efficiency-

Losses in DC motors, power flow diagram, efficiency, condition for maximum efficiency.

Testing of DC Motors:

Direct & indirect methods of testing of DC motors-Brake test, Swinburne’s test, Retardation test, Hopkinson’s test, Field’s test, merits and demerits of tests.

Three Phase Induction Motors:

Review of concept and generation of rotating magnetic field, Principle of operation, construction, classification and types; squirrel-cage, slip-ring (No question shall be set from the review portion). Slip, Torque equation, torque-slip characteristic covering motoring, generating and braking regions of operation, Maximum torque, significance of slip.

Performance of Three-Phase Induction Motor:

Phasor diagram of induction motor on no-load and on load, equivalent circuit, losses, efficiency, No-load and blocked rotor tests. Performance of the motor from the circle diagram and equivalent circuit. Cogging and crawling. High torque rotors-double cage and deep rotor bars. Equivalent circuit and performance evaluation of double cage induction motor. Induction motor working as induction generator.

Starting and Speed Control of Three-Phase Induction Motors:

Need for starter. Direct on line, Star-Delta and autotransformer starting. Rotor resistance starting. Speed control by voltage,frequency, and rotor resistance methods

Single-Phase Induction Motor:

Double revolving field theory and principle of operation. Construction and operation of split-phase, capacitor start, capacitor run, and shaded pole motors. Comparison of single phase motors and applications.

Synchronous Motor:

Principle of operation, phasor diagrams, torque and torque angle, Blondel diagram, effect of change in load, effect of change in excitation, V and inverted V curves. Synchronous condenser, hunting and damping. Methods of starting synchronous motors.

Other Motors:

Construction and operation of Universal motor, AC servomotor, Linear induction motor and stepper motors.

Course Outcomes:

At the end of the course the student will be able to:

• Explain the construction, operation and classification of DC Motor, AC motor and Special purpose motors.
• Describe the performance characteristics & applications of Electric motors.
• Demonstrate and explain the methods of testing of DC machines and determine losses and efficiency.
• Control the speed of DC motor and induction motor.
• Explain the starting methods, equivalent circuit and phasor diagrams, torque angle, effect of change in excitation and change in load, hunting and damping of synchronous motors.

Question paper pattern:

• The question paper will have ten questions.
• Each full question is for 20 marks.
• There will be 2 full questions (with a maximum of three sub questions in one full question) from each module.
• Each full question with sub questions will cover the contents under a module.
• Students will have to answer 5 full questions, selecting one full question from each module.

Text Books:

1 Electric Machines D. P. Kothari, I. J. Nagrath McGraw Hill 4th edition, 2011

2 Theory of Alternating Current Machines Alexander Langsdorf McGraw Hill 2nd Edition, 2001

3 Electric Machines Ashfaq Hussain Dhanpat Rai & Co 2nd Edition, 2013

Reference Books:

1 Electrical Machines, Drives and Power systems Theodore Wildi Pearson 6th Edition, 2014

2 Electrical Machines M.V. Deshpande PHI Learning 2013

3 Electric Machinery and Transformers Bhag S Guru at el Oxford University Press 3rd Edition, 2012

4 Electric Machinery and Transformers Irving Kosow Pearson 2rd Edition, 2012

5 Principles of Electric Machines and power Electronics P.C.Sen Wiley 2nd Edition, 2013

6 Electric Machines R.K. Srivastava Cengage Learning 2nd Edition,2013