Prelims-H8139.tex 30/3/2007 9:16 pagei Electrical Circuit Theory and Technology Prelims-H8139.tex 30/3/2007 9:16 pageii In Memory of Elizabeth Prelims-H8139.tex 30/3/2007 9:16 pageiii Electrical Circuit Theory and Technology Third edition John Bird BSc(Hons), CEng, CSci, CMath, FIET, MIEE, FIIE, FIMA, FCollT AMSTERDAM (cid:127) BOSTON (cid:127) HEIDELBERG (cid:127) LONDON (cid:127) NEW YORK (cid:127) OXFORD PARIS (cid:127) SAN DIEGO (cid:127) SAN FRANCISCO (cid:127) SINGAPORE (cid:127) SYDNEY (cid:127) TOKYO Newnes is an imprint of Elsevier Prelims-H8139.tex 30/3/2007 9:16 pageiv NewnesisanimprintofElsevierScience LinacreHouse,JordanHill,OxfordOX28DP,UK 30CorporateDrive,Suite400,Burlington,MA01803,USA Firstpublished1997 Secondedition2001 Reprinted2002 Revisedsecondedition2003 Thirdedition2007 Copyright©1997,2001,2007,JohnBird.PublishedbyElsevierLtd.Allrightsreserved TherightofJohnBirdtobeidentifiedastheauthorofthiswork hasbeenassertedinaccordancewiththeCopyright,Designs andPatentsAct1988 Nopartofthispublicationmaybereproduced,storedinaretrievalsystem ortransmittedinanyformorbyanymeanselectronic,mechanical,photocopying, recordingorotherwisewithoutthepriorwrittenpermissionofthepublisher PermissionsmaybesoughtdirectlyfromElsevier’sScience&TechnologyRights DepartmentinOxford,UK:phone(+44)(0)1865843830;fax(+44)(0)1865853333; email:permissions@elsevier.com.Alternativelyyoucansubmityourrequestonlineby visitingtheElsevierwebsiteathttp://elsevier.com/locate/permissions,andselecting ObtainingpermissiontouseElseviermaterial Notice Noresponsibilityisassumedbythepublisherforanyinjuryand/ordamagetopersons orpropertyasamatterofproductsliability,negligenceorotherwise,orfromanyuse oroperationofanymethods,products,instructionsorideascontainedinthematerial herein.Becauseofrapidadvancesinthemedicalsciences,inparticular,independent verificationofdiagnosesanddrugdosagesshouldbemade BritishLibraryCataloguinginPublicationData AcataloguerecordforthisbookisavailablefromtheBritishLibrary LibraryofCongressCataloging-in-PublicationData AcatalogrecordforthisbookisavailablefromtheLibraryofCongress ISBN-13:9780750681391 ForinformationonallNewnespublications visitourwebsiteatwww.newnespress.com TypesetbyCharonTecLtd(AMacmillanCompany),Chennai,India www.charontec.com PrintedandboundinGreatBritain Prelims-H8139.tex 30/3/2007 9:16 pagev Contents Preface xi 4.9 Safedisposalofbatteries 26 4.10 Fuelcells 26 Part1 Basicelectricalengineering 4.11 Alternative and renewable energy principles 1 sources 26 Revisiontest1 27 1 Unitsassociatedwithbasicelectrical quantities 3 1.1 SIunits 3 5 Seriesandparallelnetworks 28 1.2 Charge 3 5.1 Seriescircuits 28 1.3 Force 4 5.2 Potentialdivider 29 1.4 Work 4 5.3 Parallelnetworks 31 1.5 Power 4 5.4 Currentdivision 33 1.6 Electricalpotentialande.m.f. 5 5.5 Relativeandabsolutevoltages 36 1.7 Resistanceandconductance 5 5.6 Wiringlampsinseriesandinparallel 38 1.8 Electricalpowerandenergy 5 1.9 Summary of terms, units and their 6 Capacitorsandcapacitance 39 symbols 6 6.1 Introductiontocapacitors 39 2 Anintroductiontoelectriccircuits 7 6.2 Electrostaticfield 39 2.1 Standardsymbolsforelectrical 6.3 Electricfieldstrength 40 components 7 6.4 Capacitance 40 2.2 Electriccurrentandquantityof 6.5 Capacitors 41 electricity 7 6.6 Electricfluxdensity 42 2.3 Potentialdifferenceandresistance 8 6.7 Permittivity 42 2.4 Basicelectricalmeasuring 6.8 Theparallelplatecapacitor 43 instruments 8 6.9 Capacitorsconnectedinparalleland 2.5 Linearandnon-lineardevices 9 series 45 2.6 Ohm’slaw 9 6.10 Dielectricstrength 48 2.7 Multiplesandsub-multiples 9 6.11 Energystored 48 2.8 Conductorsandinsulators 11 6.12 Practicaltypesofcapacitor 49 2.9 Electricalpowerandenergy 11 6.13 Dischargingcapacitors 51 2.10 Maineffectsofelectriccurrent 13 2.11 Fuses 13 7 Magneticcircuits 52 7.1 Introductiontomagnetismand 3 Resistancevariation 15 magneticcircuits 52 3.1 Resistanceandresistivity 15 7.2 Magneticfields 52 3.2 Temperaturecoefficientofresistance 17 7.3 Magneticfluxandfluxdensity 53 7.4 Magnetomotiveforceandmagnetic 4 Batteries 20 fieldstrength 54 4.1 Introductiontobatteries 20 7.5 PermeabilityandB–H curves 54 4.2 Somechemicaleffectsofelectricity 20 7.6 Reluctance 56 4.3 Thesimplecell 21 7.7 Compositeseriesmagneticcircuits 57 4.4 Corrosion 22 7.8 Comparison between electrical and 4.5 E.m.f.andinternalresistanceofacell 22 magneticquantities 60 4.6 Primarycells 24 7.9 Hysteresisandhysteresisloss 60 4.7 Secondarycells 24 4.8 Cellcapacity 26 Revisiontest2 61 Prelims-H8139.tex 30/3/2007 9:16 pagevi vi Contents 8 Electromagnetism 62 11.3 Conductioninsemiconductor 8.1 Magnetic field due to an electric materials 104 current 62 11.4 Thep-njunction 104 8.2 Electromagnets 64 11.5 Forwardandreversebias 105 8.3 Forceonacurrent-carrying 11.6 Semiconductordiodes 108 conductor 65 11.7 Characteristicsandmaximum 8.4 Principleofoperationofasimple ratings 109 d.c.motor 68 11.8 Rectification 109 8.5 Principleofoperationofamoving- 11.9 Zenerdiodes 110 coilinstrument 68 11.10 Siliconcontrolledrectifiers 111 8.6 Forceonacharge 69 11.11 Lightemittingdiodes 111 11.12 Varactordiodes 111 11.13 Schottkydiodes 112 9 Electromagneticinduction 70 9.1 Introduction to electromagnetic 12 Transistors 113 induction 70 12.1 Transistorclassification 113 9.2 Lawsofelectromagneticinduction 71 12.2 Bipolarjunctiontransistors(BJT) 113 9.3 Rotation of a loop in a magnetic 12.3 Transistoraction 114 field 73 12.4 Leakagecurrent 115 9.4 Inductance 74 12.5 Biasandcurrentflow 115 9.5 Inductors 75 12.6 Transistoroperating 9.6 Energystored 76 configurations 116 9.7 Inductanceofacoil 76 12.7 Bipolartransistorcharacteristics 117 9.8 Mutualinductance 78 12.8 Transistorparameters 118 12.9 Currentgain 119 10 Electricalmeasuringinstrumentsand 12.10 TypicalBJTcharacteristicsand measurements 80 maximumratings 120 10.1 Introduction 80 12.11 Fieldeffecttransistors 121 10.2 Analogueinstruments 80 12.12 Fieldeffecttransistor 10.3 Moving-ironinstrument 81 characteristics 121 10.4 Themoving-coilrectifier 12.13 Typical FET characteristics and instrument 81 maximumratings 123 10.5 Comparisonofmoving-coil, 12.14 Transistoramplifiers 124 moving-ironandmoving-coil 12.15 Loadlines 125 rectifierinstruments 82 Revisiontest3 129 10.6 Shuntsandmultipliers 82 10.7 Electronicinstruments 84 MainformulaeforPart1 130 10.8 Theohmmeter 84 10.9 Multimeters 84 Part2 Electricalprinciplesand 10.10 Wattmeters 85 technology 131 10.11 Instrument‘loading’effect 85 10.12 Theoscilloscope 87 13 D.c.circuittheory 133 10.13 Virtualtestandmeasuring 13.1 Introduction 133 instruments 91 13.2 Kirchhoff’slaws 133 10.14 Virtualdigitalstorage 13.3 Thesuperpositiontheorem 137 oscilloscopes 92 13.4 Generald.c.circuittheory 140 10.15 Waveformharmonics 95 13.5 Thévenin’stheorem 142 10.16 Logarithmicratios 96 13.6 Constant-currentsource 146 10.17 Nullmethodofmeasurement 98 13.7 Norton’stheorem 146 10.18 Wheatstonebridge 98 13.8 Thévenin and Norton equivalent 10.19 D.C.potentiometer 99 networks 149 10.20 A.C.bridges 99 13.9 Maximumpowertransfertheorem 152 10.21 Measurementerrors 100 14 Alternatingvoltagesandcurrents 155 11 Semiconductordiodes 102 14.1 Introduction 155 11.1 Typesofmaterial 102 14.2 Thea.c.generator 155 11.2 Semiconductormaterials 102 14.3 Waveforms 156 Prelims-H8139.tex 30/3/2007 9:16 pagevii Contents vii 14.4 A.c.values 157 18.11 Analoguetodigital(A/D) 14.5 Theequationofasinusoidal conversion 222 waveform 160 Revisiontest5 224 14.6 Combinationofwaveforms 163 14.7 Rectification 166 19 Three-phasesystems 225 Revisiontest4 167 19.1 Introduction 225 19.2 Three-phasesupply 225 15 Single-phaseseriesa.c.circuits 168 19.3 Starconnection 226 15.1 Purelyresistivea.c.circuit 168 19.4 Deltaconnection 228 15.2 Purelyinductivea.c.circuit 168 19.5 Powerinthree-phasesystems 230 15.3 Purelycapacitivea.c.circuit 169 19.6 Measurementofpowerinthree- 15.4 R–Lseriesa.c.circuit 170 phasesystems 231 15.5 R–Cseriesa.c.circuit 173 19.7 Comparisonofstaranddelta 15.6 R–L–Cseriesa.c.circuit 174 connections 235 15.7 Seriesresonance 178 19.8 Advantagesofthree-phase 15.8 Q-factor 179 systems 236 15.9 Bandwidthandselectivity 180 15.10 Powerina.c.circuits 181 15.11 Powertriangleandpowerfactor 182 20 Transformers 237 20.1 Introduction 237 16 Single-phaseparallela.c.circuits 185 20.2 Transformerprincipleofoperation 237 16.1 Introduction 185 20.3 Transformerno-loadphasor 16.2 R–Lparallela.c.circuit 185 diagram 239 16.3 R–Cparallela.c.circuit 186 20.4 E.m.f.equationofatransformer 241 16.4 L–Cparallela.c.circuit 187 20.5 Transformeron-loadphasor 16.5 LR–Cparallela.c.circuit 189 diagram 242 16.6 ParallelresonanceandQ-factor 191 20.6 Transformerconstruction 244 16.7 Powerfactorimprovement 195 20.7 Equivalentcircuitofatransformer 244 20.8 Regulationofatransformer 246 17 D.c.transients 199 20.9 Transformerlossesandefficiency 246 17.1 Introduction 199 20.10 Resistancematching 249 17.2 Chargingacapacitor 199 20.11 Autotransformers 251 17.3 TimeconstantforaC–Rcircuit 200 20.12 Isolatingtransformers 253 17.4 TransientcurvesforaC–Rcircuit 200 20.13 Three-phasetransformers 253 17.5 Dischargingacapacitor 204 20.14 Currenttransformers 254 17.6 Cameraflash 206 20.15 Voltagetransformers 255 17.7 CurrentgrowthinanL–Rcircuit 206 Revisiontest6 256 17.8 TimeconstantforanL–Rcircuit 207 17.9 TransientcurvesforanL–Rcircuit 207 17.10 CurrentdecayinanL–Rcircuit 208 21 D.c.machines 257 17.11 Switchinginductivecircuits 211 21.1 Introduction 257 17.12 Theeffectoftimeconstantona 21.2 Theactionofacommutator 257 rectangularwaveform 211 21.3 D.c.machineconstruction 258 21.4 Shunt,seriesandcompound 18 Operationalamplifiers 212 windings 258 18.1 Introductiontooperational 21.5 E.m.f. generated in an armature amplifiers 212 winding 259 18.2 Someopampparameters 213 21.6 D.c.generators 260 18.3 Opampinvertingamplifier 214 21.7 Typesofd.c.generatorandtheir 18.4 Opampnon-invertingamplifier 216 characteristics 261 18.5 Opampvoltage-follower 217 21.8 D.c.machinelosses 264 18.6 Opampsummingamplifier 217 21.9 Efficiencyofad.c.generator 265 18.7 Opampvoltagecomparator 218 21.10 D.c.motors 265 18.8 Opampintegrator 219 21.11 Torqueofad.c.machine 266 18.9 Opampdifferentialamplifier 220 21.12 Typesofd.c.motorandtheir 18.10 Digitaltoanalogue(D/A) characteristics 268 conversion 221 21.13 Theefficiencyofad.c.motor 271 Prelims-H8139.tex 30/3/2007 9:16 pageviii viii Contents 25 Applicationofcomplexnumberstoparallel 21.14 D.c.motorstarter 273 a.c.networks 316 21.15 Speedcontrolofd.c.motors 274 25.1 Introduction 316 21.16 Motorcooling 276 25.2 Admittance,conductanceand susceptance 316 22 Three-phaseinductionmotors 277 25.3 Parallela.c.networks 319 22.1 Introduction 277 25.4 Furtherworkedproblemson 22.2 Productionofarotatingmagnetic parallela.c.networks 323 field 277 22.3 Synchronousspeed 279 26 Powerina.c.circuits 327 22.4 Constructionofathree-phase 26.1 Introduction 327 inductionmotor 280 26.2 Determinationofpowerin 22.5 Principle of operation of a three- a.c.circuits 327 phaseinductionmotor 280 26.3 Powertriangleandpowerfactor 329 22.6 Slip 281 26.4 Useofcomplexnumbersfor 22.7 Rotore.m.f.andfrequency 282 determinationofpower 330 22.8 Rotorimpedanceandcurrent 283 26.5 Powerfactorimprovement 334 22.9 Rotorcopperloss 283 Revisiontest8 339 22.10 Inductionmotorlossesand efficiency 284 27 A.c.bridges 340 22.11 Torque equation for an induction 27.1 Introduction 340 motor 285 27.2 Balance conditions for an a.c. 22.12 Inductionmotortorque–speed bridge 340 characteristics 287 27.3 Typesofa.c.bridgecircuit 341 22.13 Starting methods for induction 27.4 Workedproblemsona.c.bridges 345 motors 288 22.14 Advantagesofsquirrel-cage 28 SeriesresonanceandQ-factor 349 inductionmotors 290 28.1 Introduction 349 22.15 Advantagesofwoundrotor 28.2 Seriesresonance 349 inductionmotor 290 28.3 Q-factor 351 22.16 Doublecageinductionmotor 290 28.4 Voltagemagnification 353 22.17 Usesofthree-phaseinduction 28.5 Q-factorsinseries 355 motors 290 28.6 Bandwidth 356 28.7 Smalldeviationsfromtheresonant Revisiontest7 291 frequency 360 MainformulaeforPart2 292 29 ParallelresonanceandQ-factor 362 29.1 Introduction 362 Part3 Advancedcircuittheoryand 29.2 TheLR–Cparallelnetwork 363 technology 295 29.3 Dynamicresistance 363 29.4 TheLR–CRparallelnetwork 363 23 Revisionofcomplexnumbers 297 29.5 Q-factorinaparallelnetwork 364 23.1 Introduction 297 29.6 Furtherworkedproblemson 23.2 OperationsinvolvingCartesian parallelresonanceandQ-factor 368 complexnumbers 298 Revisiontest9 371 23.3 Complexequations 300 23.4 Thepolarformofacomplex 30 Introductiontonetworkanalysis 372 number 301 30.1 Introduction 372 23.5 Multiplicationanddivisionusing 30.2 Solutionofsimultaneous complexnumbersinpolarform 301 equationsusingdeterminants 372 23.6 De Moivre’s theorem — powers 30.3 Networkanalysisusing androotsofcomplexnumbers 303 Kirchhoff’slaws 374 24 Applicationofcomplexnumberstoseries 31 Mesh-currentandnodalanalysis 381 a.c.circuits 305 31.1 Mesh-currentanalysis 381 24.1 Introduction 305 31.2 Nodalanalysis 385 24.2 Seriesa.c.circuits 305 24.3 Furtherworkedproblemsonseries 32 Thesuperpositiontheorem 391 a.c.circuits 311 32.1 Introduction 391 Prelims-H8139.tex 30/3/2007 9:16 pageix Contents ix 32.2 Usingthesuperpositiontheorem 391 38.3 Hysteresisandhysteresisloss 488 32.3 Further worked problems on the 38.4 Eddycurrentloss 491 superpositiontheorem 396 38.5 Separationofhysteresisandeddy currentlosses 494 33 Thévenin’sandNorton’stheorems 400 38.6 Non-permanentmagnetic 33.1 Introduction 400 materials 496 33.2 Thévenin’stheorem 400 38.7 Permanentmagneticmaterials 497 33.3 Further worked problems on Revisiontest12 499 Thévenin’stheorem 406 33.4 Norton’stheorem 410 39 Dielectricsanddielectricloss 500 33.5 Thévenin and Norton equivalent 39.1 Electricfields,capacitanceand networks 417 permittivity 500 Revisiontest10 422 39.2 Polarization 500 39.3 Dielectricstrength 501 34 Delta-starandstar-deltatransformations 423 39.4 Thermaleffects 502 34.1 Introduction 423 39.5 Mechanicalproperties 502 34.2 Deltaandstarconnections 423 39.6 Typesofpracticalcapacitor 502 34.3 Delta-startransformation 423 39.7 Liquiddielectricsandgas 34.4 Star-deltatransformation 431 insulation 502 39.8 Dielectriclossandlossangle 502 35 Maximumpowertransfertheoremsand impedancematching 435 40 Fieldtheory 506 35.1 Maximumpowertransfer 40.1 Fieldplottingbycurvilinear theorems 435 squares 506 35.2 Impedancematching 440 40.2 Capacitancebetweenconcentric Revisiontest11 443 cylinders 510 40.3 Capacitance of an isolated twin 36 Complexwaveforms 444 line 514 36.1 Introduction 444 40.4 Energystoredinanelectricfield 517 36.2 Thegeneralequationfora 40.5 Inducede.m.f.andinductance 519 complexwaveform 444 40.6 Inductanceofaconcentric 36.3 Harmonicsynthesis 446 cylinder(orcoaxialcable) 519 36.4 Fourierseriesofperiodicand 40.7 Inductanceofanisolatedtwinline 522 non-periodicfunctions 453 40.8 Energystoredinanelectro- 36.5 Evenandoddfunctionsand magneticfield 524 Fourierseriesoveranyrange 457 36.6 Rmsvalue,meanvalueandthe 41 Attenuators 527 formfactorofacomplexwave 462 41.1 Introduction 527 36.7 Power associated with complex 41.2 Characteristicimpedance 528 waves 465 41.3 Logarithmicratios 529 36.8 Harmonicsinsingle-phasecircuits 467 41.4 SymmetricalT-andπ-attenuators 531 36.9 Furtherworkedproblemson 41.5 Insertionloss 536 harmonicsinsingle-phasecircuits 471 41.6 AsymmetricalT-andπ-sections 539 36.10 Resonanceduetoharmonics 474 41.7 TheL-sectionattenuator 542 36.11 Sourcesofharmonics 476 41.8 Two-portnetworksincascade 544 41.9 ABCDparameters 546 37 Anumericalmethodofharmonicanalysis 480 41.10 ABCDparametersfornetworks 550 37.1 Introduction 480 41.11 Characteristicimpedanceinterms 37.2 Harmonic analysis on data given ofABCDparameters 555 intabularorgraphicalform 480 Revisiontest13 557 37.3 Complexwaveform considerations 483 42 Filternetworks 558 42.1 Introduction 558 38 Magneticmaterials 486 42.2 Basictypesoffiltersections 558 38.1 Revision of terms and units used 42.3 The characteristic impedance and withmagneticcircuits 486 theattenuationoffiltersections 560 38.2 Magneticpropertiesofmaterials 487 42.4 Laddernetworks 561