Electrical Machines

Md. Abdus Salam, PhD, is a professor at Fanshawe College, Ontario and an adjunct research professor in the Department of Electrical and Computer Engineering at Western University, Ontario with over 24 years of teaching experience. He has published eight textbooks, 58 articles in international journals, and 66 papers in international conferences. In addition to his academic work, he has served as a consultant for various private and government agencies. He is a senior member of the Institute of Electrical and Electronics Engineers, USA and a member of the Institution of Engineering Technology, UK.

• Preface xvAcknowledgement xvii1 Analysis of Electrical Power 11.1 Introduction 11.2 Power 11.3 Average Power and Reactive Power 51.4 Apparent Power 101.5 Complex Power 131.6 Complex Power Balance 201.7 Power Factor and Reactive Factor 241.8 Power Factor Correction 251.9 Three-Phase Voltage Generation 321.10 Phase Sequence 341.11 Wye Connection 351.12 Analysis of Wye Connection 361.13 Delta Connection 411.14 Analysis of Delta Connection 421.15 Analysis of Three-Phase Power 451.16 Basic Measurement Equipment 54Exercise Problems 552 Magnetic Circuits 612.1 Introduction 612.2 Magnetic Force and Field 612.3 Magnetic Circuit 652.4 Magnetic Flux and Magnetic Flux Density 652.5 Magnetomotive Force 682.6 Magnetizing Force 692.7 Permeability and Relative Permeability 712.8 Reluctance 732.9 Permeance 752.10 Fleming’s Rules 772.11 Analogy of Magnetic and Electric Circuits 782.12 Ampere’s Circuital Law 792.13 Magnetic Flux Density of a Long Straight Wire 802.14 Toroidal Coil 822.15 Series Magnetic Circuit 842.16 Parallel Magnetic Circuit 882.17 Air Gap 922.18 Analysis of Magnetic Circuit with Air Gap 932.19 Electromagnetic Force on a Conductor 982.20 Force Between Two Parallel Conductors 1032.21 Faraday’s Laws 1042.22 Magnetic Materials and B-H Curve 1052.23 Inductance and Mutual Inductance 1082.24 Hysteresis Curve and Losses 114Exercise Problems 1173 Transformer 1233.1 Introduction 1233.2 Working Principle of Transformer 1253.3 Transformer Flux 1263.4 Construction of a Transformer 1273.5 Ideal Transformer 1283.6 E.M.F. Equation of Transformer 1293.7 Turns Ratio of Transformer 1313.8 Analysis of No-Load Phasor Diagram 1363.9 Analysis of Load Phasor Diagram 1383.10 Rules for Referring Impedance 1383.11 Equivalent Circuit of a Transformer 1423.12 Exact Equivalent Circuit 1433.13 Approximate Equivalent Circuit 1463.14 Polarity of a Transformer 1493.15 Three-Phase Transformer 1503.16 Transformer Vector Group 1523.17 Voltage Regulation of a Transformer 1603.18 Efficiency of a Transformer 1653.19 Iron and Copper Losses 1663.20 Maximum Efficiency 1683.21 Transformer Tests 1713.22 Autotransformer 1773.23 Parallel Operation of a Single-Phase Transformer 1813.24 Three-Phase Transformer Connections 1863.25 Instrument Transformers 1943.26 Transformer Oil Testing and Cooling 1953.27 All-Day Efficiency of Transformer 197Exercise Problems 1994 Direct Current Generators 2074.1 Introduction 2074.2 Electromagnetic Induction 2084.3 Motional Voltage 2094.4 Lenz’s Law 2124.5 Working Principle 2134.6 Construction of a DC Generator 2164.7 Armature Coils and Windings 2174.8 Induced EMF of a DC Generator 2214.9 Classification of a DC Generator 2254.10 Separately Excited DC Generator 2254.11 Self-Excited DC Generator 2274.12 Series Generator 2274.13 Shunt Generator 2284.14 Compound Generator 2314.15 Saturation Curve of a DC Generator 2374.16 Generator Build-Up Process 2414.17 Voltage Build-Up Failure Reasons 2434.18 Field Circuit Resistance Lines 2434.19 Theory of Commutation 2444.20 Armature Reaction 2464.21 Demagnetizing and Cross-Magnetizing 2494.22 Cancellation of Armature Reaction 2524.23 Series Generator Characteristics 2544.24 Shunt Generator Characteristics 2554.25 Compound Generator Characteristics 2564.26 Applications of a DC Generator 2584.27 Voltage Regulation of DC Generator 2584.28 Losses of a DC Generator 2604.29 Efficiency of a DC Generator 2614.30 Parallel Operation of a DC Generator 265Exercise Problems 2675 Direct Current Motors 2715.1 Introduction 2715.2 Working Principle 2725.3 Construction 2735.4 Back EMF 2745.5 Necessity of Back EMF 2765.6 Classification of a DC Motor 2765.7 Mechanical Power of a DC Motor 2825.8 Torque of a DC Motor 2865.9 Speed of a DC Motor 2905.10 Speed Regulation of a DC Motor 2945.11 Losses in a DC Motor 2955.12 Efficiency of a DC Motor 2975.13 Characteristics of a DC Motor 3025.14 Characteristics of a Shunt Motor 3025.15 Characteristics of a Series Motor 3045.16 Characteristics of a Cumulative Compound Motor 3075.17 Comparison Between Generator and Motor 3095.18 Application of DC Motors 309Exercise Problems 3106 Control and Starting of DC Motors 3156.1 Introduction 3156.2 Speed Controlling Parameters 3156.3 Flux Control Method 3166.4 Armature Control Method 3186.5 Armature Voltage Control Method 3226.6 Speed Control of a Series Motor 3236.7 Ward Leonard System 3296.8 Semiconductor Devices 3306.9 Half-Wave Rectifier 3326.10 Full-Wave Rectifier 3366.11 Speed Control by Thyristor and Diode 3416.12 Braking of a DC Motor 3446.13 DC Motor Starter 3496.14 Three-Point Starter 3496.15 Four-Point Starter 3506.16 Grading of Starting Resistance 351Exercise Problems 3607 Three-Phase Induction Motor 3657.1 Introduction 3657.2 Construction 3667.3 Working Principle 3687.4 Rotating Field 3697.5 Synchronous Speed and Slip Speed 3747.6 Rotor Frequency and Speed 3767.7 Rotor Voltage and Rotor Reactance 3787.8 Rotor Torque 3807.9 Starting Torque 3817.10 Running Torque 3867.11 Relationship Between Torques 3897.12 Equivalent Circuit 3937.13 Power Relationships 4007.14 Approximate Equivalent Circuit 4047.15 Condition for Maximum Mechanical Power 4057.16 Power Stages 4107.17 Torque-Slip Characteristics 4137.18 Linear Induction Motor 4157.19 Classification of Induction Motor by Properties 419Exercise Problems 4208 Starting and Control of an Induction Motor 4238.1 Introduction 4238.2 Direct Starting 4238.3 Variable Resistance Starter 4268.4 Autotransformer Starter 4278.5 Star-Delta Starter 4308.6 Simple Magnetic Starter 4348.7 Forward-Reverse Starter 4378.8 Cogging and Crawling 4418.9 Importance of Deep Bar and Double Cage Rotor 4428.10 Double Squirrel Cage Motor 4458.11 Determination of Equivalent Circuit Parameters 4498.12 Speed Control of Induction Motor 4568.13 Automatic Star-Delta Starter 461Exercise Problems 4639 Synchronous Generator 4659.1 Introduction 4659.2 Construction 4669.3 Pole and Frequency 4699.4 Working Principle 4719.5 Full-Pitch and Short-Pitch Windings 4739.6 Pitch or Chording Factor 4769.7 Distribution Factor 4819.8 Effect of Harmonics on Pitch and Distribution Factors 4849.9 EMF Equation of an Alternator 4869.10 Equivalent Circuit of Synchronous Generator 4949.11 Phasor Diagrams 4969.12 Voltage Regulation 5009.13 Tests of a Synchronous Generator 5019.14 Power and Torque Expressions 5079.15 Salient Pole Synchronous Generator 5139.16 Power of a Salient Pole Generator 5179.17 Parallel Operation of an Alternator 5269.18 Load Sharing of Alternators 5309.19 Synchronization of Alternators 5329.20 Capability Curve of Alternators 535Exercise Problems 53910 Synchronous Motor 54310.1 Introduction 54310.2 Construction 54310.3 Working Principle 54410.4 Starting of Synchronous Motor 54610.5 Equivalent Circuit 54810.6 Phasor Diagrams 54910.7 Synchronous Impedance Diagrams 55210.8 Effect of Different Field Excitations 55310.9 Power of Cylindrical Rotor 56010.10 Various Conditions of Power 56610.11 Phasor Diagrams of Salient Pole Motor 57610.12 Power Expression of Salient Pole Motor 58310.13 V-Curves of a Synchronous Motor 58810.14 Power Factor Correction 59110.15 Hunting of a Synchronous Motor 59910.16 Applications of Synchronous Motor 60010.17 Comparison of Synchronous Motor and Induction Motor 600Exercise Problems 60111 Single-Phase Induction Motors 60311.1 Introduction 60311.2 Construction and Synchronous Speed 60311.3 Double Revolving Field Theory 60511.4 Working Principle 60711.5 Slip 60911.6 Equivalent Circuit 61111.7 Classification of a Single-Phase Motor 61711.8 Starting of Single-Phase Motors 61711.9 AC Series Motor 63111.10 Reluctance and Hysteresis Motors 63811.11 Test of a Single-Phase Motor 64411.12 Stepper Motor 65011.13 Step Angle of Stepper Motor 65211.14 Permanent Magnet Stepper Motor 65411.15 Variable-Reluctance Stepper Motor 65711.16 Hybrid Stepper Motor 663Exercise Problems 665References 667Index 669