/ 1 ELECTRICAL AND ELECTRONIC TECHNOLOGY EDWARD HUGHES Revised by John Hiley, Keith Brown and Ian McKenzie Smith Hariow, England London New York Boston San Francisco Toronto Sydney Singapore Hong Kong Tokyo Seoul Taipei New Delhi Cape Town Madrid Mexico City Amsterdam Munich Paris Milan
Contents Prefaces Section 1 Electrical Principles 1 International System of Measurement 1.1 The International System 1.2 SI derived units 1.3 Unit of turning moment or torque 1.4 Unit of work or energy 1.5 Unit of power 1.6 Efficiency 1.7 Temperature 2 Introduction to Electrical Systems 2.1 Electricity and the engineer 2.2 An electrical system 2.3 Electric charge 2.4 Movement of electrons 2.5 Current flow in a circuit 2.6 Electromotive force and potential difference 2.7 Electrical units 2.8 Ohm's law 2.9 Resistors 2.10 Resistor coding 2.11 Conductors and insulators 2.12 The electric circuit in practice 3 Simple DC Circuits 3.1 Series circuits 3.2 Parallel networks 3.3 Series circuits versus parallel networks 4 5 6 7 8 9 10 10 11 2 13 13 15 15 16 16 17 20 22 23 25 26 27 28 0 31 36 41 3.4 Kirchhoff's laws 3.5 Power and energy 3.6 Resistivity 3.7 Temperature coefficient of resistance 3.8 Temperature rise 4 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10 4.11 5 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 5.10 5.11 Network Theorems New circuit analysis techniques Kirchhoff's laws and network solution Mesh analysis Nodal analysis Superposition theorem Thevenin's theorem The constant-current generator Norton's theorem Delta-star transformation Star delta transformation Maximum power transfer Capacitance and Capacitors Capacitors Hydraulic analogy Charge and voltage Capacitance Capacitors in parallel Capacitors in series Distribution of voltage across capacitors in series Capacitance and the capacitor Electric fields Electric field strength and electric flux density Relative t>ermittivitv 42 49 52 54 56 57 58 61 62 62 70 72 75 77 81 84 86 87 88 89 89 92 93 94 95 95 96 96 97 98 99 99 101
viii 5.12 Capacitance of a multi-plate capacitor 102 5.13 Composite-dielectric capacitors 103 5.14 Charging and discharging currents 106 5.15 Growth and decay 107 5.16 Analysis of growth and decay 109 5.17 Discharge of a capacitor through a resistor 112 5.18 Transients in CR networks 114 5.19 Energy stored in a charged capacitor 119 5.20 Force of attraction between oppositely charged plates > 120 5.21 Dielectric strength 121 5.22 Leakage and conduction currents in capacitors 122 5.23 Displacement current in a dielectric 123 5.24 Types of capacitor and capacitance 123 126 127 6 Electromagnetism 132 8 Inductance in a DC Circuit 8.1 Inductive and non-inductive circuits 8.2 Unit of inductance 8.3 Inductance in terms of flux-linkages per ampere 8.4 Factors determining the inductance of a coil 8.5 Ferromagnetic-cored inductor in a d.c. circuit 8.6 Growth in an inductive circuit 8.7 Analysis of growth 8.8 Analysis of decay 8.9 Transients in LR networks 8.10 Energy stored in an inductor 8.11 Mutual inductance 8.12 Coupling coefficient 8.13 Coils connected in series 8.14 Types of inductor and inductance 162 163 164 166 169 171 172 175 177 179 182 185 188 189 191 192 193 6.1 Magnetic field 133 6.2 Direction of magnetic field 133 6.3 Characteristics of lines of magnetic flux 133 6.4 Magnetic field due to an electric current 134 6.5 Magnetic field of a solenoid 135 6.6 Force on a current-carrying conductor 136 6.7 Force determination 138 6.8 Electromagnetic induction 140 6.9 Direction of induced e.m.f. 140 6.10 Magnitude of the generated or induced e.m.f. 141 6.11 Magnitude of e.m.f. induced in a coil 143 145 145 7 Simple Magnetic Circuits 147 7.1 Introduction to magnetic circuits 148 7.2 Magnetomotive force and magnetic field strength 148 7.3 Permeability of free space or magneticconstant 149 7.4 Relative permeability 151 7.5 Reluctance 153 7.6 Comparison of electric and magnetic circuits 154 7.7 Determination of the B/H characteristic 156 7.8 Comparison of electromagnetic and electrostatic terms 158 158 159 9 Alternating Voltage and Current 197 9.1 Alternating systems 198 9.2 Generation of an alternating e.m.f. 198 9.3 Waveform terms and definitions 202 9.4 Relationship between frequency, speed and number of pole pairs 204 9.5 Average and r.m.s. values of an alternating current 204 9.6 Average and r.m.s. values of sinusoidal currents and voltages 206 9.7 Average and r.m.s. values of non-sinusoidal currents and voltages 211 9.8 Representation of an alternating quantity by a phasor 212 9.9 Addition and subtraction of sinusoidal alternating quantities 214 9.10 Phasor diagrams drawn with r.m.s. values instead of maximum values 216 9.11 Alternating system frequencies in practice 217 218 218 10 Single-phase Series Circuits 222 10.1 Basic a.c. circuits 223 10.2 Alternating current in a resistive circuit 223 10.3 Alternating current in an inductive circuit 224 10.4 Current and voltage in an inductive circuit 226
IX 10.5 Mechanical analogy of an inductive circuit 228 10.6 Resistance and inductance in series 229 10.7 Alternating current in a capacitive circuit 232 10.8 Current and voltage in a capacitive circuit 233 10.9 Analogies of a capacitance in an a.c. circuit 234 10.10 Resistance and capacitance in series 234 10.11 Alternating current in an RLC circuit 236 240 241 11 Single-phase Parallel Networks 243 11.1 Basic a.c. parallel circuits 244 11.2 Simple parallel circuits 244 11.3 Parallel impedance circuits 248 11.4 Polar impedances 252 11.5 Polar admittances 255 257 257 12 Power in AC Circuits 259 12.1 The impossible power 260 12.2 Power in a resistive circuit 260 12.3 Power in a purely inductive circuit 261 12.4 Power in a purely capacitive circuit 263 12.5 Power in a circuit with resistance and reactance 264 12.6 Power factor 266 12.7 Active and reactive currents 268 12.8 The practical importance of power factor 270 12.9 Measurement of power in a single-phase circuit 271 271 271 13 Complex Notation 273 13.1 The j operator 274 13.2 Addition and subtraction of phasors 275 13.3 Voltage, current and impedance 276 13.4 Admittance, conductance and susceptance 279 13.5 RL series circuit admittance 280 13.6 RC series circuit admittance 280 13.7 Parallel admittance 281 13.8 Calculation of power, using complex notation 285 286 287 14 Resonance in AC Circuits 290 14.1 14.2 14.3 14.4 14.5 14.6 14.7 14.8 14.9 14.10 14.11 14.12 14.13 14.14 14.15 Introduction 291 Frequency variation in a series RLC circuit 291 The resonant frequency of a series RLC circuit 294 The current in a series RLC circuit Voltages in a series RLC circuit Quality factor Q Oscillation of energy at resonance Mechanical analogy of a resonant circuit Series resonance using complex notation Bandwidth Selectivity Parallel resonance Current magnification Parallel and series equivalents The two-branch parallel resonant circuit 15 Network Theorems Applied to AC Networks 15.1 One stage further 15.2 Kirchhoff's laws and network solution 15.3 Nodal analysis 15.4 Superposition theorem 15.5 Thevenin's theorem 15.6 Norton's theorem 15.7 Star delta transformation 15.8 Delta-star transformation 15.9 Maximum power transfer 16 Micropower or Megapower 16.1 Introduction 16.2 System efficiency 16.3 Effects of waste heat 16.4 The length of the circuit 16.5 Accuracy 16.6 The way ahead 294 294 295 297 298 298 299 301 304 305 306 307 310 310 313 314 314 321 321 323 328 332 333 335 336 340 341 341 342 343 344 345 345 Section 2 Electronic Engineering 347 17 Electronic Systems 17.1 Introduction to systems 17.2 Electronic systems 349 350 351
17.3 Basic amplifiers 17.4 Basic attenuators 17.5 Block diagrams 17.6 Layout of block diagrams 18 Passive Filters 18.1 Introduction 18.2 Types of filter 18.3 Frequency response 18.4 Logarithms 18.5 Log scales 18.6 The decibel (db) 18.7 The low-pass or lag circuit 18.8 The high-pass or lead circuit 18.9 Passband (or bandpass) filter 18.10 Stopband (or bandstop) filters 18.11 Bode plots 351 354 354 355 355 355 356 357 357 359 359 362 363 366 370 373 376 376 382 383 19 Amplifier Equivalent Networks 385 19.1 Amplifier constant-voltage equivalent networks 386 19.2 Amplifier constant-current equivalent networks 388 19.3 Logarithmic units 390 19.4 Frequency response 393 19.5 Feedback 395 19.6 Effect of feedback on input and output resistances 399 19.7 Effect of feedback on bandwidth 401 19.8 Distortion 401 402 402 20 Semiconductor Materials 405 20.1 Introduction 406 20.2 Atomic structure 406 20.3 Covalent bonds 407 20.4 An n-type semiconductor 409 20.5 A p-type semiconductor 410 20.6 Junction diode 411 20.7 Construction and static characteristics of a junction diode 414 416 21 Rectifiers 417 21.1 Rectifier circuits 418 21.2 Half-wave rectifier 418 21.3 Full-wave rectifier network 421 21.4 Bridge rectifier network 422 21.5 Smoothing 425 21.6 Zener diode 427 428 429 22 Junction Transistor Amplifiers 22.1 Introduction 22.2 Bipolar junction transistor 22.3 Construction of a bipolar transistor 22.4 Common-base and common-emitter circuits 22.5 Static characteristics for a common-base circuit 22.6 Static characteristics for a common-emitter circuit 22.7 Relationship between a and /3 22.8 Load line for a transistor 22.9 Transistor as an amplifier 22.10 Circuit component selection 22.11 Equivalent circuits of a transistor 22.12 Hybrid parameters 22.13 Limitations to the bipolar junction transistor 22.14 Stabilizing voltage supplies 22.15 Transistor as a switch 23 FET Amplifiers 23.1 Field effect transistor (FET) 23.2 JUGFET 23.3 IGFET 23.4 Static characteristics of a FET 23.5 Equivalent circuit of a FET 23.6 The FET as a switch 431 432 432 433 433 434 435 436 437 439 445 446 450 451 452 456 456 457 462 463 463 465 467 467 469 470 470 24 Further Semiconductor Amplifiers 472 24.1 Cascaded amplifiers 24.2 Integrated circuits 473 477
xi 24.3 Operational amplifiers 478 24.4 The inverting operational amplifier 479 24.5 The summing amplifier 480 24.6 The non-inverting amplifier 482 24.7 Differential amplifiers 482 24.8 Common-mode rejection ratio 484 485 485 25 Interfacing Digital and Analogue Systems 488 25.1 The need for conversion 489 25.2 Digital-to-analogue conversion 489 25.3 D/A converter hardware 492 25.4 D/A converters in practice 494 25.5 RI1R ladder D/A converter 496 25.6 Analogue-to-digital conversion 497 25.7 Simple comparator 499 25.8 A/D converters 500 25.9 Converters in action 502 503 26 Digital Numbers 506 26.1 Introduction 507 26.2 Binary numbers 507 26.3 Decimal to binary conversion 508 26.4 Binary addition 509 26.5 Binary subtraction 510 26.6 Binary multiplication 510 26.7 Binary division 511 26.8 Negative binary numbers 513 26.9 Signed binary addition 514 26.10 Signed binary subtraction 515 26.11 Signed binary multiplication 516 26.12 Signed binary division 517 26.13 The octal system 518 26.14 Hexadecimal numbers 519 520 27 Digital Systems 521 27.1 Introduction to logic 522 27.2 Basic logic statements or functions 522 27.3 The OR function 522 27.4 The AND function 523 27.5 The EXCLUSIVE-OR function 523 27.6 The NOT function 524 27.7 Logic gates 524 27.8 The NOR function 525 27.9 The NAND function 525 27.10 Logic networks 526 27.11 Combinational logic 527 27.12 Gate standardization 530 27.13 Karnaugh maps for simplifying combinational logic 533 27.14 Bistable multivibrator circuits 540 27.15 Registers 541 27.16 Timing diagrams 542 27.17 Integrated circuit logic gates 543 544 545 28 Microprocessors and Programs 548 28.1 28.2 28.3 28.4 28.5 28.6 28.7 28.8 28.9 28.10 28.11 28.12 28.13 28.14 28.15 Microprocessors Microprocessor operation Microprocessor control Programs Simple programs Control programs Programming in hexadecimal representation The programmable logic controller Control system characteristics Flexibility of PLCs Inside a PLC The PLC program Input devices Outputs A practical application 29 Control Systems 29.1 Introduction 29.2 Open-loop and closed-loop systems 29.3 Automation 29.4 Components of a control system 29.5 Transfer function 29.6 Regulators and servomechanisms 29.7 In transient periods 29.8 Damping 549 549 552 556 559 561 563 566 567 567 568 569 571 572 572 577 580 581 582 583 583 584 585 587 588 591
XII 30 Signals 593 30.1 Classification of signals 594 30.2 Representation of a signal by a continuum of impulses 600 30.3 Impulse response 602 30.4 Convolution sum for discrete-time systems 602 30.5 Convolution integral for continuous-time systems 605 30.6 Deconvolution 606 30.7 Relation between impulse response and unit step response 607 30.8 Step and impulse responses of discrete-time systems 608 609 610 31 Data Transmission and Signals 612 31.1 Transmission of information 613 31.2 Analogue signals 613 31.3 Digital signals 614 31.4 Bandwidth 616 31.5 Modulation 617 31.6 Filters 619 31.7 Demodulation 620 31.8 Amplifying signals 621 31.9 Digital or analogue? 622 623 32 Communications 624 32.1 Basic concepts 625 32.2 Information theory for source coding 627 32.3 Data communications systems 629 32.4 Coding for efficient transmission 630 32.5 Source coding 633 635 635 33 Fibreoptics 637 33.1 Introduction 638 33.2 Fibre loss 638 33.3 Refraction 639 33.4 Light acceptance 641 33.5 Attenuation 33.6 Bandwidth 33.7 Modulation 33.8 Optical fibre systems Section 3 Power Engineering 34 Multiphase Systems 34.1 Disadvantages of the single-phase system 34.2 Generation of three-phase e.m.f.s 34.3 Delta connection of three-phase windings 34.4 Star connection of three-phase windings 34.5 Voltages and currents in a star-connected system 34.6 Voltages and currents in a delta-connected system 34.7 Power in a three-phase system with a balanced load 34.8 Measurement of active power in a three-phase, three-wire system 34.9 Power factor measurement by means of two wattmeters 34.10 Two-phase systems 35 Transformers 35.1 Introduction 35.2 Core factors 35.3 Principle of action of a transformer 35.4 EMF equation of a transformer 35.5 Phasor diagram for a transformer on no load 35.6 Phasor diagram for an ideal loaded transformer 35.7 Useful and leakage fluxes in a transformer 35.8 Leakage flux responsible for the inductive reactance of a transformer 35.9 Methods of reducing leakage flux 35.10 Equivalent circuit of a transformer 35.11 Phasor diagram for a transformer on load 35.12 Approximate equivalent circuit of a transformer 35.13 Simplification of the approximate equivalent circuit of a transformer 35.14 Voltage regulation of a transformer 641 642 643 643 644 645 647 649 650 650 651 652 655 656 659 660 662 665 666 667 670 671 671 672 673 675 677 679 681 681 682 683 684 685 686
xiii 35.15 Efficiency of a transformer 690 35.16 Condition for maximum efficiency of a transformer 691 35.17 Open-circuit and short-circuit tests on a transformer 693 35.18 Calculation of efficiency from the open-circuit and short-circuit tests 694 35.19 Calculation of the voltage regulation from * the short-circuit test 694 35.20 Three-phase core-type transformers 696 35.21 Auto-transformers 696 35.22 Current transformers 697 35.23 Waveform of the magnetizing current of a transformer 698 35.24 Air-cored transformer 699 700 700 36 Introduction to Machine Theory 704 36.1 The role of the electrical machine 705 36.2 Conversion process in a machine 705 36.3 Methods of analysis of machine performance 707 36.4 Magnetic field energy 708 36.5 Simple analysis of force of alignment 709 36.6 Energy balance 710 36.7 Division of converted energy and power 713 36.8 Force of alignment between parallel magnetized surfaces 714 36.9 Rotary motion 717 36.10 Reluctance motor 718 36.11 Doubly excited rotating machines 720 722 722 37 AC Synchronous Machine Windings 726 38 Characteristics of AC Synchronous Machines 739 38.1 Armature reaction in a three-phase synchronous generator 740 38.2 Voltage regulation of a synchronous generator 742 38.3 Synchronous impedance 742 38.4 Parallel operation of synchronous generators 745 38.5 Three-phase synchronous motor: principle of action 747 38.6 Advantages and disadvantages of the synchronous motor 748 748 39 Induction Motors 39.1 Principle of action 39.2 Frequency of rotor e.m.f. and current 39.3 Rotor e.m.f. and current 39.4 Relationship between the rotor I 2 R loss and the rotor slip 39.5 Factors determining the torque 39.6 Variation of torque with slip, other factors remaining constant 39.7 Effect of rotor resistance upon the torque/sli] relationship 39.8 Starting torque 39.9 Starting of a three-phase induction motor fitted with a cage rotor 39.10 Comparison of cage and slip-ring rotors 39.11 Braking 39.12 Single-phase induction motors 39.13 Capacitor-run induction motors 39.14 Split-phase motors 39.15 Shadcd-pole motors 750 751 752 753 755 756 756 757 758 759 760 761 762 764 764 765 766 766 37.1 General arrangement of synchronous machines 727 37.2 Types of rotor construction 727 37.3 Stator windings 729 37.4 Expression for the e.m.f. of a stator winding 732 37.5 Production of rotating magnetic flux by three-phase currents 732 37.6 Analysis of the resultant flux due to three-phase currents 734 37.7 Reversal of direction of rotation of the magnetic flux 736 737 737 40 Power Systems 40.1 System representation 40.2 Power system analysis 40.3 Voltage-drop calculations 40.4 The per-unit method 40.5 Per-unit impedance 40.6 Base power - S n or MVA B 40.7 Faults in a power system 40.8 Representation of a grid connection 769 770 771 772 775 776 778 781 784 786 786
xiv 41 Direct-current Machines 789 41.1 General arrangement of a d.c. machine 41.2 Double-layer drum windings 41.3 Calculation of e.m.f. generated in an armature winding 41.4 Armature reaction 41.5 Armature reactiop in a d.c. motor 41.6 Commutation * 42 Direct-current Motors 42.1 Armature and field connections 42.2 A d.c. machine as generator or motor 42.3 Speed of a motor 42.4 Torque of an electric motor 42.5 Speed characteristics of electric motors 42.6 Torque characteristics of electric motors 42.7 Speed control of d.c. motors 790 791 794 795 798 799 801 801 43 Control System Motors 820 43.1 43.2 43.3 43.4 43.5 43.6 43.7 43.8 44 44.1 44.2 44.3 44.4 44.5 44.6 44.7 44.8 44.9 Review Motors for regulators RPC system requirements Geneva cam The stepping (or stepper) motor The variable-reluctance motor The hybrid stepping motor Drive circuits Motor Selection and Efficiency Selecting a motor Speed Power rating and duty cycles Load torques The motor and its environment Machine efficiency Hysteresis Current-ring theory of magnetism Hysteresis loss 03 804 804 806 807 809 810 811 817 817 821 821 822 823 823 824 825 827 828 830 831 831 832 833 834 835 836 836 838 44.10 Losses in motors and generators 841 44.11 Efficiency of a d.c. motor 843 44.12 Approximate condition for maximum 44.13 45 45.1 45.2 45.3 45.4 45.5 45.6 45.7 45.8 45.9 45.10 45.11 45.12 efficiency Determination of efficiency Power Electronics Introductory Thyristor Some thyristor circuits Limitations to thyristor operation The thyristor in practice The fully controlled a.c./d.c. converter AC/DC inversion Switching devices in inverters Three-phase rectifier networks The three-phase fully controlled converter Inverter-fed induction motors Soft-starting induction motors Section 4 Measurements 46.1 46.2 46.3 46.4 46.5 46.6 46.7 46.8 46.9 46.10 844 844 847 849 850 850 852 854 854 854 855 858 859 861 861 862 863 864 47 Analogue Measuring Instruments 887 47.1 47.2 47.3 865 46 Electronic Measuring Instruments 867 Introduction to analogue and electronic instruments Digital electronic voltmeters Digital electronic ammeters and wattmeters Graphical display devices The two-electrode vacuum device Control of the anode current Cathode-ray tube Deflecting systems of a cathode-ray tube Cathode-ray oscilloscope Use of the cathode-ray oscilloscope in waveform measurement 868 869 871 871 872 873 873 874 875 879 885 Introduction 888 Electrical analogue indicating instruments 888 Controlling devices 889
XV 47.4 Damping devices 47.5 Permanent-magnet moving-coil ammeters and voltmeters 47.6 Thermocouple instruments 47.7 Electrodynamic (or dynamometer) instruments 47.8 Electrostatic voltmeters 47.9 Rectifier ammeters and voltmeters 47.10 Measurement of resistance by the Wheatstone bridge 47.11 The potentiometer 47.12 A commercial form of potentiometer 890 894 894 896 896 897 898 899 47.13 Standardization of the potentiometer 47.14 Calibration of an ammeter by means of a potentiometer 47.15 Calibration accuracy and errors 47.16 Determination of error due to instrument errors Appendix: Symbols, Abbreviations, Definitions and Diagrammatic Symbols Answers to Exercises Index 900 900 900 903 908 911 916 927 Supporting resource Visit www.pearsoned.co.uk/hughes to find a valuable online resource For instructors Complete, downloadable Instructor's Manual For more information please contact your local Pearson Education sales representative or visit www.pearsoned.co.uk/hughes