Synopses & Reviews
A practical blend of theory, diagrams, graphs, drawings, and photos combine in this book to assist readers in developing a complete understanding of all types of electric motors, generators, and alternators. All About Motors comprehensively examines such concepts as magnetic and inductive theory, characteristics of various types of motors, and the speed control of AC and DC motors that provide the necessary background for a thorough understanding of rotating equipment. Basic concepts of rotation are skillfully applied to the complex theories of rotor phase angles and their effect on torque so technicians learn effective service and troubleshooting techniques as well as motor operations. The knowledge gained will give students a foundation to develop into journeymen who can be counted on to successfully handle all aspects of the electrical industry.
About the Author
NJATC develops and standardizes training for National Electrical Contractors Association and the International Brotherhood of Electrical Workers, which represents more than 780,000 memebers working in a wide variety of fields around North America.
Table of Contents
CHAPTER 1- Rules, Glossary, and Formulas: 1.1 Electrical Rules, 1.2 Glossary of Electrical Terms, 1.3 Formulas. CHAPTER 2- Magnetism, Electromagnetism, and Induction (Basic, Self-, and Mutual): 2.1 Magnetism, 2.2 Electromagnetism, 2.3 Induction. CHAPTER 3- AC Alternators: 3.1 Introduction, 3.2 Construction of the Stator, 3.3 Construction of the Rotor, 3.4 Types of Alternators, 3.5 Theory of Operation, 3.6 Determining Alternator Frequencies, 3.7 Rating Alternators, 3.8 Output Voltage of Alternators, 3.9 Resistance, Reactance, and Reaction of Alternators, 3.10 Paralleling Alternators, 3.11 Load Sharing, 3.12 Shutting Down One Unit. CHAPTER 4- The Rotating Field in the Polyphase Motor: 4.1 Origin of the Rotating Field, 4.2 Effect of Alternator Poles on Motor Speed, 4.3 Frequency and its Effects on Rotation, 4.4 Rotation in a Two-Pole Delta, 4.5 Rotation in a Two-Pole Wye. CHAPTER 5- Polyphase Motors: 5.1 Reading the Nameplate of the Polyphase Motor, 5.2 Construction of the Stator, 5.3 Construction of the Rotor, 5.4 Stator Windings in a Wye Connection, 5.5 Stator Windings in a Delta Connection, 5.6 Foreign Motors: Delta-Low and Wye-High Connections, 5.7 U.S. Motors on 50 Hz, 5.8 Polyphase ACA or Shunt-Commutator Motors, 5.9 Classification of Motors According to Rotor Design, 5.10 Efficiency of Polyphase Motors, 5.11 Power Factor in Polyphase Motors, 5.12 Motor Losses, 5.13 Operating Characteristics of Polyphase Motors, 5.14 Consequent-Pole Polyphase Motors, 5.15 Multispeed Polyphase Motors, 5.16 Nema StandardsCHAPTER 6: Wound-Rotor Motors, 6.1 Construction of the Stator, 6.2 Speed of the Wound-Rotor Motor (Stator), 6.3 Applications, 6.4 Construction of the Rotor, 6.5 Operating Characteristics, 6.6 Locked-Rotor Stator Currents, 6.7 Monitoring Rotor Currents, 6.8 Torque of the WRM, 6.9 Speed Control of the WRM, 6.10 Efficiency of the WRM, 6.11 Starters of the WRM with Pneumatic-Timing Acceleration Control, 6.12 Starters of the WRM with Compensated Acceleration Control, 6.13 Regulators of the WRM. CHAPTER 7- Synchronous Motors: 7.1 Construction of the Stator, 7.2 Construction of the Rotor, 7.3 Reduced Voltage Starting (Stator), 7.4 Applications, 7.5 Starting the Synchronous Motor, 7.6 The Polarized-Frequency Relay, 7.7 The Out-Of-Step Relay, 7.8 The Exciter Generator, 7.9 The AC Ammeter, 7.10 The DC Ammeter , 7.11 Operating Characteristics, 7.12 Power-Factor Correction Using a Synchronous Motor, 7.13- The Brushless Synchronous Motor. CHAPTER 8- The Alternating Field in a Single-Phase Motor: 8.1 Alternating Field in a Single-Phase Motor, 8.2 Phase Shift in a Single-Phase Motor, 8.3 Placement of Phase Shift (Start Winding) in the Stator8.4 Operating Characteristics, 8.5 Adding Capacitance: Its Effect on Phase Shift, 8.6 Reversing Phase Shift in a Single-Phase Motor, 8.7 Rotation of Fields in a Single-Phase Motor. CHAPTER 9- Single-Phase Motors: 9.1 Construction of the Stator, 9.2 Construction of the Rotor, 9.3 Split-Phase Motors, 9.4 Multispeed Split-Phase Motors, 9.5 Capacitor-Start Motors, 9.6 Multispeed Capacitor-Start Motors, 9.7 Capacitor-Start, Capacitor-Run Motors, 9.8 Permanent Split-Capacitor Motors, 9.9 Multispeed Permanent Split-Capacitor Motors, 9.10 Shaded-Pole Motors, 9.11 Repulsion-Type Motors. CHAPTER 10- DC Motors: 10.1 Introduction to DC Motors, 10.2 Counter Electromotive Force, 10.3 Dynamic Braking, 10.4 Torque of a DC Motor, 10.5 RPM in a DC Motor, 10.6 Speed Regulation in DC Motors, 10.7 Armature Reaction, 10.8 The DC Motor Assembly, 10.9 The Commutator, 10.10 Brush Types, 10.11 Commutation, 10.12 Interpoles, 10.13 Compensating Windings, 10.14 Setting Brush Neutral, 10.15 Types of Armature Windings, 10.16 Series DC Motors, 10.17 Shunt DC Motors, 10.18 Compound DC Motors. CHAPTER 11- DC Generators11.1 Introduction to DC Generators, 11.2 Construction of the Generator, 11.3 Comparison of the Generator to the Motor, 11.4 Brushes in the Generator, 11.5 The Commutator, 11.6 Commutation, 11.7 Interpoles in the Generator, 11.8 Setting Brush Neutral in the Generator, 11.9 The Electromotive Force in the Generator, 11.10 Voltage Regulation in DC Generator, 11.11 DC Series Generator, 11.12 DC Shunt Generator, 11.13 DC Compound Generator. CHAPTER 12- Starting and Braking of Motors, 12.1 Across-the-Line Starting, 12.2 Reduced Voltage Starting, 12.3 Wye-Start, Delta-Run Motor, 12.4 Autotransformer Reduced-Voltage Starting, 12.5 Impedance (Reactor) Reduced-Voltage Starting, 12.6 Primary-Resistance Starting, 12.7 Dynamic Braking, 12.8 Mechanical Braking. CHAPTER 13- Principles of Electronic Variable-Speed Control, 13.1 Overview of Variable-Speed Drives, 13.2 Motor Operating Speed, 13.3 Speed-Control Methods, 13.4 Basic Electronic Variable-Speed Drive Components, 13.5 Typical Electronic-Drive Circuitry, 13.6 Electronic-Drive Terminology. CHAPTER14- Electronic DC Variable-Speed Drives: 14.1 Electronic DC Variable-Speed Drive Selection Parameters, 14.2 Field-Current Controllers, 14.3 SCR-Armature Voltage Control, 14.4 Chopper-Armature Voltage Control, 14.5 Duty-Cycle and Pulse-Width Modulation, 14.6 Forms A, B, C, and D Control Circuits, 14.7 Forms C and D Power Circuits: Examples, 14.8 Drive Selection and Application. CHAPTER 15- Electronic AC Variable-Speed Drives: 15.1 Two Types of AC Variable-Speed Drives, 15.2 Variable-Voltage Drives, 15.3 Pulse-Width Modulation, 15.4 Variable-Frequency Drives, 15.5 Voltage-Source and Current-Source Drives, 15.6 AC Drive Selection and Installation. CHAPTER 16 Eddy-Current and Magnetic Clutches, 16.1 Introduction to Eddy-Current Clutches, 16.2 Eddy-Current Clutch Ratings, 16.3 Operation of the Eddy-Current Clutch, 16.4 Construction of the Eddy-Current Clutch, 16.5 Cooling of the Eddy-Current Clutch, 16.6 Comparing the Eddy-Current Clutch to the Friction Clutch, 16.7 The Magnetic Friction Clutch. CHAPTER 17-Troubleshooting Motors: 17.1 Introduction to Troubleshooting, 17.2 Troubleshooting Single-Phase Motors, 17.3 Troubleshooting Polyphase Motors, 17.4 Troubleshooting DC Motors, 17.5 Troubleshooting Test Instruments, 17.6 Identifying Unmarked Motor Leads. CHAPTER 18 Rotating Single-Phase to Three-Phase Converters, 18.1 Selecting the Type of Three-Phase Power, 18.2 Theory of the Rotary Converter, 18.3 Building the Three-Phase Converter. CHAPTER 19- Other Motors: 19.1 Introduction to Other Motors, 19.2 Universal AC/DC Motors, 19.3 Variable-Reluctance Motors, 19.4 Hysteresis Motors, 19.5 Stepper Motors, 19.6 High-Frequency Motors, 19.7 Linear-Induction Motors, 19.8 Outer-Rotor Motors, 19.9 Selsyn Motors (Servos), 19.10 Two-Phase Motors, 19.11 induction motors as Generators. CHAPTER 20- Installing Motors, Pulleys, and Couplings: 20.1 Introduction to Installation, 20.2 Power-Factor Correction, 20.3 Location of Capacitors, 20.4 Installation of the Motor, 20.5 Direct Coupling of the Motor to the Load, 20.6 Offset Coupling of the Motor to the Load, 20.7 Ratios of the Drive/Driven Pulleys, 20.8 Speed of the Belt, 20.9 Sample Worksheets,