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The University of LahoreDepartment of Electrical Engineering

Course Title: DC and AC Machines

Credit Hours: 4

Course Instructor: Nazim Siddique

Semester: fall - 2011

Course Objectives: This course has been designed to teach the students the fundamentals of DC and AC Machines with special emphasis on practical understanding and simulation on Matlab (Simulink).In this course the students would be studying an introduction of electromechanical energy conversion system, to introduce the students with the fundamental concepts, various types of electrical machines, the machinery principles, construction, working principle and operation of DC motor and generator, single phase machines, synchronous generator and motor, induction motor and transformer along with the basic experimental skills for handling problems associated with these electrical machines.

Learning Outcomes: After completing the course with a grade of C (2.0/4.0) or better, the student should be able to do the following:

Be familiar with machinery principles. Be able to understand the production of magnetic field, properties of ferromagnetic

materials, effect of magnetic field to its surroundings and magnetic circuit. Be able to explore a linear machine model for good starting point in the study of real

machines. Be able to differentiate the real, reactive and apparent power in ac circuits. Be able to understand the construction and working of DC machines. Be able to explore the commutation problems in DC machine and their solutions. Be able to draw the development diagram of lap and wave winding. Be able to model the equivalent circuit of a real DC motor. Be able to explore the power and torque limits as a function of speed for a shunt

motor under armature voltage and field resistance control. Be able to explore the terminal characteristic of DC generators. Be able to understand the construction and operation of the transformer. Be able to model the equivalent circuit of a real transformer. Be able to differentiate the voltage regulation at unity, lagging and leading power

factor. Be able to explore the terms and condition for parallel operation of transformers. Be able to understand condition for maximum efficiency in a transformer. Be able to proof the concept of rotating magnetic field and its reversing by swapping

any two phases.

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Be able to understand the construction, operation and modeling of synchronous machine.

Be able to explore harmonic problem in synchronous machines and their suppression techniques.

Be able to view the effects of load changes on synchronous generator alone. Be familiar with the condition required for parallel operation of synchronous

generators. Be able to explore the frequency-power and voltage-reactive power characteristic of a

synchronous generator. Be able to understand the steady-state operation of a synchronous motor. Be able to understand the starting problem of synchronous motor and their solution Be able to differentiate the equivalent model of the transformer and induction motor. Be able to explore the torque-speed characteristic of an induction motor. Be able to model the equivalent circuit of a real induction motor. Be able to understand the concept of double-revolving-field theory and cross-field

theory for single phase induction motor. Be able to understand the staring techniques of single-phase induction motors.

Course Pre-Requisite Network Analysis

Recommended Text Books:Electric Machinery Fundamentals (4th Edition)By: Stephen J.Chapman.

Reference Text:

1) Electric Machines Theory,Operation,Application,adjustment and Control (2nd Edition)By: Charles I. Hubert

2) Electric Machines By: Smarajit Ghosh

Lecture Wise Topic AssignmentLec no.

Topic Sub Topics Reading Assign.

1 Course introduction2 Introduction Electrical machines, Transformers and

daily life, units and notation, rotational motion, Newton’s law and power relationship, angular position, angular velocity, acceleration ,torque ,Newton’s

Ch 1 (SJC)

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Lec no.

Topic Sub Topics Reading Assign.

Law of rotation, work and power.

3 Magnetic fieldProduction of magnetic field and magnetic circuits.

Ch 1 (SJC)

4 Magnetic field

Magnetic behavior of ferromagnetic material, energy losses in a ferromagnetic material, faraday’s law, production of force on a current carrying wire in magnetic field and induced voltage on a conductor moving in a magnetic field.

Ch 1 (SJC)

5The linear DC machines

Starting a linear DC machine, the linear machine as a motor, and as a generator.

Ch 1 (SJC) Ass.No.1

6DC machinery fundamentals

Voltage and torque induced in a simple rotating loop, Commutation in a simple four-loop DC machine, problems with commutation in real machine (armature reaction and L di/dt voltage) and their solution techniques.

Ch 8 (SJC)

7DC machinery fundamentals(continuous)

Lap and wave winding, pole, front, back, commutatore and resultant pitch. Progressive and retrogressive winding. Power flow and losses in DC machines

Ch 8 (SJC)

8 DC motors

Equivalent circuit and magnetization curve of a DC motor, separately excited DC shunt motors, terminal characteristic and nonlinear analysis of a shunt DC motor, speed control of shunt DC motors

Ch 9 (SJC)

9 DC generators

The separately excited DC generator and its terminal characteristic. The DC shunt generator and its voltage buildup process. Terminal characteristic of DC series and compound generator

Ch 9 (SJC) Quiz no.1

10AC power and circuit’s power factor

Real, reactive and apparent power in single phase/three phase AC circuit and the power triangle.

Ch 1 (SJC)

11A simple loop in a uniform magnetic field

The voltage induce in a simple rotating loop, the torque induce in a current carrying loop.

Ch 4 (SJC)

12 The rotating Proof of rotating magnetic field, reversing

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Lec no.

Topic Sub Topics Reading Assign.

magnetic field.

the direction of magnetic field of rotation and the relationship between the electrical frequency and speed of magnetic field rotation.

Ch 4 (SJC)

13

Flux distribution , induce voltage / torque in an AC machine and power flow diagram

The induce voltage in a coil on a two pole stator, the RMS voltage in three phase stator .Voltage regulation and speed regulation.

Ch 4 (SJC)

14

Synchronous generator construction and its equivalent circuit

Armature winding, field winding, salient pole and non salient pole rotor, brushless exciting circuit, speed of rotation of a synchronous generator, armature reaction, synchronous reactance ,stator resistance

Ch 5 (SJC)

15

The effect of coil pitch on ac machine

Pitch of a coil, full pitch coil, fractional pitch coil, voltage induce in fractional pitch winding, distributed winding, coil span factor and distribution factor

Appendix B

16

Measurement of model parameters ,power and torque in synchronous generator,

Open circuit test, short circuit test, power flow diagram of synchronous generator, losses in synchronous generator, condition for maximum power transformation.

Ch 5 (SJC)

17

Operation of single generation and parallel operation of synchronous generators

The effects of load change on a synchronous generator operating alone, condition required for parallel operation, frequency-power and voltage-reactive power characteristic, operation of generators in parallel with large power system and with other generators of same size.

Ch 5 (SJC) Mid term

18Steady-state synchronous motor operation

Torque speed characteristic, effect of load change and field change on a synchronous generator.

Ch 6 (SJC)

19

Starting of synchronous motor

Motor staring by reduced electrical frequency, with an external prim mover, by using damping winding.

Ch 6 (SJC)

20 Induction motor construction and

Stator winding, cage rotor, wound rotor, development of torque, slip, electrical

Ch 7 (SJC)

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Lec no.

Topic Sub Topics Reading Assign.

its equivalent circuit

frequency on the rotor, transformer model of an induction motor and rotor circuit model.

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Power and torque characteristic

Losses and power-flow diagram, power and torque equations, derivation of induced-torque equation, torque-speed characteristic, starting and pullout torque.

Ch 7 (SJC)

22

Variation in torque-speed characteristic and determination of circuit model parameters

Control of characteristic by cage rotor design, no load test, the DC test for stator resistance and locked rotor test.

Ch 7 (SJC) Ass.No.2

23

Transformer, its construction and types.Ideal transformer.

Importance of transformer in modern life, shell type, core type, unit transformer, distribution transformer, substation transformer. Power in ideal transformer and impedance transformation through a transformer.

Ch 2 (SJC)

24Theory and operation of real transformer

Dot convention, voltage and current ratio, transformer at no load and transformer at load.

Ch 2 (SJC)

25Equivalent circuit of transformer

EMF equation. Of a transformer. Exact equivalent, approximate equivalent circuit and determination of component’s values in transformer model.

Ch 2 (SJC) Quiz no.2

26Voltage regulation and efficiency, Auto transformer.

Phasor diagram of transformer at resistive load, inductive load, capacitive load and its efficiency. Condition for maximum efficiency. Voltage and current relationship, power rating advantage, internal impedance in auto transformer.

Ch 2 (SJC)

27

Three phase transformers, parallel operation of transformers.

Three phase transformer Δ- Δ, Δ- Y, Y- Δ, Y- Y connection. Condition for parallel operation.

Ch 2 (SJC)

28

Transformer ratting related problem and instrument transformers.

The voltage and frequency rating of a transformer, Apparent power ratting, problem of current inrush, current transformer and potential transformer

Ch 2 (SJC)

29 Single phase and Working and application of universal Ch 10

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Lec no.

Topic Sub Topics Reading Assign.

special purpose motors.

motor, double-revolving field and cross field theory of single-phase induction motor.

(SJC)

30Starting single-phase I.M

Split-phase and Capacitor-type winding, shaded stator poles and stepper motor

Ch 10 (SJC)

Final Exam

Grading Policy:

Labs 20 %Assignments 10 %Quizzes 10 %Mid-Term 20 %Final 40 %

Attendance Policy:All students must have minimum of 75% attendance to be eligible to appear in the final exam.