Alternating current fundamentals

747 Pages·2011·11.795 MB·English

by  Stephen L Herman, John R Duff

ALTERNATING
CURRENT
FUNDAMENTALS
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ALTERNATING
CURRENT
FUNDAMENTALS
EIGHTH EDITION
Stephen L. Herman
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Contents
PREFACE ix
UNIT 1
Introduction to Alternating Current 1
• Introduction • Angular relationships • Alternating-voltage generation • Frequency • Electrical time
degrees and mechanical degrees • Other waveforms • Higher frequencies
UNIT 2
Alternating-Current Circuits Containing Resistance 23
• Current and voltage in phase • Heating effect of an alternating current • Effective (RMS) voltage
• Resistance • Power in watts • Electrical energy • Measurement of energy • Average current and
voltage
UNIT 3
Inductance in Alternating-Current Circuits 43
• Review of electromagnetism • Inductive reactance • Vector addition and subtraction • Resistance
and inductive reactance in series • Power and power factor
UNIT 4
Series Circuits—Resistance and Impedance 72
• Effective resistance • Skin effect • Eddy current losses • Hysteresis losses • Dielectric losses
• Resistance and inductance in series • Figure of merit
UNIT 5
Capacitors and RC Time Constants 97
• Introduction • Capacitance • Dielectric characteristics • Capacitance formulas • Capacitors in parallel
• Capacitors in series • Capacitors in network systems • Energy in a capacitor • RC time constants • RL
time constants • Applications of capacitors • Types of capacitors • Capacitor markings
v
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vi CONTENTS
UNIT 6
Capacitors in Alternating-Current Circuits 137
• Capacitive reactance • Leading current • Angle of phase defect • Voltage rating of a capacitor
• Power in a capacitor • Capacitors in parallel and in series • Magnetizing VARs • Diagrams for the
series circuit
UNIT 7
Series Circuits: Resistance, Inductive Reactance,
and Capacitive Reactance 161
• Series RLC circuit • Resonance in series circuits • The properties of series resonance
UNIT 8
AC Parallel Circuits 189
• Introduction • Parallel circuit with resistive load • Parallel circuit with branches containing R and X
L
• Parallel circuit with branches containing R and X • Parallel circuit with branches containing R and
C
Z • Parallel circuit with branches containing R, X , and X • Parallel circuit resonance • Parallel
coil L C
circuit with branches containing R, Z , and X • Correcting motor power factor
coil C
UNIT 9
Series–Parallel Circuits 231
• Admittance, conductance, and susceptance
UNIT 10
Three-Phase Systems 242
• Introduction • Three-phase voltage • Phase sequence • The wye connection • Power in the wye sys-
tem • The delta connection • Power in the delta system • Power measurement in three-phase systems
• The three-wattmeter method • Two-phase system
UNIT 11
AC Instruments and Meters 276
• Measurements of AC quantities • Measurement of voltage and current • Rectifier instruments
with d’Arsonval movement • Other types of AC voltmeter and ammeter movements • Ammeters
and voltmeters • Practical ranges for moving iron instruments • The dynamometer wattmeter • Two-
element wattmeter for three-phase system • Varmeters • Power factor meters • Synchroscopes
• Frequency meters • Recording instruments • Thermal converters • The watt-hour meter • Digital
multimeters • Clamp-on ammeters • The oscilloscope
UNIT 12
Alternating-Current Generators 328
• Introduction • Revolving armature-type alternator • Revolving field-type alternator • The stator
windings • Ventilation • Operation of a rotating field • Armature voltage losses (neglecting
armature reaction) • Synchronous impedance (with armature reaction) • Automatic voltage control
• Saturation curve • Alternator nameplate data • Alternator efficiency • Paralleling alternators
• Hunting
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CONTENTS vii
UNIT 13
Transformers 386
• Transformer efficiency • The exciting current • Primary and secondary voltage relationships
• Primary and secondary current relationships • Leakage flux • Exciting current and core losses
• Copper losses using direct current • Transformer losses and efficiency • Polarity markings • ASA
and NEMA standards • Transformers in parallel • The distribution transformer • The single-phase,
three-wire system • Transformer characteristics • Transformer construction • Transformer inrush
current • Magnetic domains • Multiple tapped windings • Cooling transformers • Tap-changing
transformers • Frequency and voltage • Transformer impedance • Transformer nameplate data
UNIT 14
Transformer Connections for Three-Phase Circuits 439
• The delta connection • Feeding a dual load • The wye connection • Delta–wye connection
• Wye-delta connections • Open-delta connection • Three-phase transformers • T-connected
transformers • Scott connection • Zigzag connection • Three-phase-to-six-phase connections
• Harmonics • Circuit breaker problems • Bus ducts and panel problems
UNIT 15
Special Transformer Applications 492
• Instrument transformers • Autotransformers • Constant-current transformers • Induction voltage
regulator
UNIT 16
Three-Phase Induction Motors 521
• Three-phase, squirrel-cage induction motor • The rotating magnetic field • Synchronous speed
• Percent slip • Rotor frequency • Torque and speed characteristics • Starting characteristics • Power
factor • Summary of operating characteristics • Procedure for measuring motor losses • Speed control
• Code letter identification • Motor nameplate data • Stator winding connections • Single-phase
operation of three-phase induction motors • The wound-rotor induction motor • Reverse rotation
• Terminal markings • Operating characteristics • Comparison between squirrel-cage and wound-
rotor induction motors
UNIT 17
The Synchronous Motor 569
• Construction • Operating principles • DC field excitation • Load on a synchronous motor • Power
factor • Industrial applications • Starting large synchronous motors • Synchronous motor ratings
• Small single-phase synchronous motors • Selsyn motors • Operation • Selsyn differential system
UNIT 18
Single-Phase Motors 599
• Introduction • Single-phase induction motors • Resistance-start, induction-run motor • Capacitor-start,
induction-run motor • Capacitor-start, capacitor-run motor • Multispeed motor • Repulsion-type motors
• Repulsion motor • Repulsion-start, induction-run motor • Repulsion–induction motor • Alternating-
current series motor • Conductive and inductive compensation • Shaded-pole induction motor • Variable-
speed motors • Stepping motors
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viii CONTENTS
UNIT 19
Control Circuits 646
• Two-wire circuits • Three-wire circuits • Electrical symbols for pilot/control devices • Schematic
and wiring diagrams • Interlocking • Jogging • Timers • Wound-rotor motor control
APPENDICES 665
ANSWERS TO PRACTICE PROBLEMS 695
GLOSSARY 709
INDEX 717
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