Visit to download the full and correct content document: https://ebookmeta.com/product/electric-fuses-fundamentals-and-new-applications-4th -edition-nigel-p-m-nurse/
new
Electric Fuses: Fundamentals and
applications 4th Edition Nigel P.M. Nurse
More products digital (pdf, epub, mobi) instant download maybe you interests ...
Nuclear and Radiochemistry Fundamentals and Applications 4th Edition Kratz
https://ebookmeta.com/product/nuclear-and-radiochemistryfundamentals-and-applications-4th-edition-kratz/
Pulsed Electric Fields Technology for the Food Industry Fundamentals and Applications 2nd Edition Javier Raso
https://ebookmeta.com/product/pulsed-electric-fields-technologyfor-the-food-industry-fundamentals-and-applications-2nd-editionjavier-raso/
Fluid Mechanics: Fundamentals and Applications 4th Ed in SI 4th Edition Yunus A. Çengel
https://ebookmeta.com/product/fluid-mechanics-fundamentals-andapplications-4th-ed-in-si-4th-edition-yunus-a-cengel/
Electric and Hybrid Vehicles: Design Fundamentals 3rd Edition Iqbal Husain
https://ebookmeta.com/product/electric-and-hybrid-vehiclesdesign-fundamentals-3rd-edition-iqbal-husain/
Fundamentals of Electric Aircraft 1st Edition Pascal Thalin
https://ebookmeta.com/product/fundamentals-of-electricaircraft-1st-edition-pascal-thalin/
Primary Mathematics 3A Hoerst
https://ebookmeta.com/product/primary-mathematics-3a-hoerst/
Fundamentals of Electric Circuits 7th Edition Charles K. Alexander
https://ebookmeta.com/product/fundamentals-of-electriccircuits-7th-edition-charles-k-alexander/
Boatowner s Mechanical and Electrical Manual 4th Edition Nigel Calder
https://ebookmeta.com/product/boatowner-s-mechanical-andelectrical-manual-4th-edition-nigel-calder/
Electric Power Applications 2nd Edition Federico Barrero Mario Bermúdez
https://ebookmeta.com/product/electric-power-applications-2ndedition-federico-barrero-mario-bermudez/
ElectricFuses
IETENERGYENGINEERINGSERIES191
Othervolumesinthisseries:
Volume1
Powercircuitbreakertheoryanddesign C.H.Flurscheim(Editor)
Volume4 Industrialmicrowaveheating A.C.MetaxasandR.J.Meredith
Volume7 Insulatorsforhighvoltages J.S.T.Looms
Volume8
VariablefrequencyACmotordrivesystems D.Finney
Volume10 SF6switchgear H.M.RyanandG.R.Jones
Volume11
Volume13
Conductionandinductionheating E.J.Davies
Statisticaltechniquesforhighvoltageengineering W.Hauschildand W.Mosch
Volume14 Uninterruptablepowersupplies J.PlattsandJ.D.StAubyn(Editors)
Volume15 Digitalprotectionforpowersystems A.T.JohnsandS.K.Salman
Volume16 Electricityeconomicsandplanning T.W.Berrie
Volume18 Vacuumswitchgear A.Greenwood
Volume19 Electricalsafety:aguidetocausesandpreventionofhazards J.MaxwellAdams
Volume21
Volume22
Volume24
Electricitydistributionnetworkdesign,2ndedition E.Lakerviand E.J.Holmes
Artificialintelligencetechniquesinpowersystems K.Warwick,A.O.Ekwue andR.Aggarwal(Editors)
Powersystemcommissioningandmaintenancepractice K.Harker
Volume25 Engineers’handbookofindustrialmicrowaveheating R.J.Meredith
Volume26 Smallelectricmotors H.Moczala etal.
Volume27 AC-DCpowersystemanalysis J.ArrillandB.C.Smith
Volume29 Highvoltagedirectcurrenttransmission,2ndedition J.Arrillaga
Volume30 FlexibleACTransmissionSystems(FACTS) Y-H.Song(Editor)
Volume31 Embeddedgeneration N.Jenkins etal.
Volume32 Highvoltageengineeringandtesting,2ndedition H.M.Ryan(Editor)
Volume33 Overvoltageprotectionoflow-voltagesystems,revisededition P.Hasse
Volume34 Thelightningflash V.Cooray
Volume35 Controltechniquesdrivesandcontrolshandbook W.Drury(Editor)
Volume36 Voltagequalityinelectricalpowersystems J.Schlabbach etal.
Volume37 Electricalsteelsforrotatingmachines P.Beckley
Volume38 Theelectriccar:developmentandfutureofbattery,hybridandfuel-cell cars M.Westbrook
Volume39 Powersystemselectromagnetictransientssimulation J.Arrillagaand N.Watson
Volume40 Advancesinhighvoltageengineering M.HaddadandD.Warne
Volume41 Electricaloperationofelectrostaticprecipitators K.Parker
Volume43 Thermalpowerplantsimulationandcontrol D.Flynn
Volume44 Economicevaluationofprojectsintheelectricitysupplyindustry H.Khatib
Volume45 Propulsionsystemsforhybridvehicles J.Miller
Volume46 Distributionswitchgear S.Stewart
Volume47 Protectionofelectricitydistributionnetworks,2ndedition J.Gersand E.Holmes
Volume48 Woodpoleoverheadlines B.Wareing
Volume49 Electricfuses,3rdedition A.WrightandG.Newbery
Volume50 Windpowerintegration:connectionandsystemoperationalaspects B.Fox etal.
Volume51 Shortcircuitcurrents J.Schlabbach
Volume52 Nuclearpower J.Wood
Volume53 Conditionassessmentofhighvoltageinsulationinpowersystem equipment R.E.JamesandQ.Su
Volume55 Localenergy:distributedgenerationofheatandpower J.Wood
Volume56 Conditionmonitoringofrotatingelectricalmachines P.Tavner,L.Ran, J.PenmanandH.Sedding
Volume57 TheControlTechniquesDrivesandControlsHandbook,2ndEdition B.Drury
Volume58 LightningProtection V.Cooray(Editor)
Volume59 UltracapacitorApplications J.M.Miller
Volume62 LightningElectromagnetics V.Cooray
Volume63 EnergyStorageforPowerSystems,2ndEdition A.Ter-Gazarian
Volume65 ProtectionofElectricityDistributionNetworks,3rdEdition J.Gers
Volume66 HighVoltageEngineeringTesting,3rdEdition H.Ryan(Editor)
Volume67 MulticoreSimulationofPowerSystemTransients F.M.Uriate
Volume68 DistributionSystemAnalysisandAutomation J.Gers
Volume69 TheLighteningFlash,2ndEdition V.Cooray(Editor)
Volume70 EconomicEvaluationofProjectsintheElectricitySupplyIndustry, 3rdEdition H.Khatib
Volume72 ControlCircuitsinPowerElectronics:Practicalissuesindesignand implementation M.Castilla(Editor)
Volume73 WideAreaMonitoring,ProtectionandControlSystems:Theenablerfor SmarterGrids A.VaccaroandA.Zobaa(Editors)
Volume74 PowerElectronicConvertersandSystems:Frontiersandapplications A.M.Trzynadlowski(Editor)
Volume75 PowerDistributionAutomation B.Das(Editor)
Volume76 PowerSystemStability:Modelling,analysisandcontrol A.A.Sallamand B.OmP.Malik
Volume78 NumericalAnalysisofPowerSystemTransientsandDynamics A.Ametani (Editor)
Volume79 Vehicle-to-Grid:Linkingelectricvehiclestothesmartgrid J.Luand J.Hossain(Editors)
Volume81 Cyber-Physical-SocialSystemsandConstructsinElectricPower Engineering S.Suryanarayanan,R.RocheandT.M.Hansen(Editors)
Volume82 PeriodicControlofPowerElectronicConverters F.Blaabjerg,K.Zhou, D.WangandY.Yang
Volume86 AdvancesinPowerSystemModelling,ControlandStabilityAnalysis F.Milano(Editor)
Volume87 Cogeneration:Technologies,OptimisationandImplentation C.A. Frangopoulos(Editor)
Volume88 SmarterEnergy:fromSmartMeteringtotheSmartGrid H.Sun, N.Hatziargyriou,H.V.Poor,L.CarpaniniandM.A.Sa ´ nchezFornie ´ (Editors)
Volume89 HydrogenProduction,SeparationandPurificationforEnergy A.Basile, F.Dalena,J.TongandT.N.Veziroglu(Editors)
Volume90 CleanEnergyMicrogrids S.ObaraandJ.Morel(Editors)
Volume91 FuzzyLogicControlinEnergySystemswithDesignApplicationsin Matlab/Simulink‡ I ˙ .H.Altas ¸
Volume92 PowerQualityinFutureElectricalPowerSystems A.F.ZobaaandS.H.E.A. Aleem(Editors)
Volume93 CogenerationandDistrictEnergySystems:Modelling,Analysisand Optimization M.A.RosenandS.Koohi-Fayegh
Volume94 IntroductiontotheSmartGrid:Concepts,technologiesandevolution S.K.Salman
Volume95 Communication,ControlandSecurityChallengesfortheSmartGrid S.M. MuyeenandS.Rahman(Editors)
Volume96 IndustrialPowerSystemswithDistributedandEmbedded Generation RBelu
Volume97 SynchronizedPhasorMeasurementsforSmartGrids M.J.B.ReddyandD.K. Mohanta(Editors)
Volume98 LargeScaleGridIntegrationofRenewableEnergySources A.MorenoMunoz(Editor)
Volume100 ModelingandDynamicBehaviourofHydropowerPlants N.Kishorand J.Fraile-Ardanuy(Editors)
Volume101 MethaneandHydrogenforEnergyStorage R.CarriveauandD.S-K.Ting
Volume104 PowerTransformerConditionMonitoringandDiagnosis A.Abu-Siada (Editor)
Volume106 SurfacePassivationofIndustrialCrystallineSiliconSolarCells J.John (Editor)
Volume107 BifacialPhotovoltaics:Technology,applicationsandeconomics J.Libal andR.Kopecek(Editors)
Volume108 FaultDiagnosisofInductionMotors J.Faiz,V.GhorbanianandG.Joksimovi ´ c
Volume109 CoolingofRotatingElectricalMachines: Fundamentals,modelling,testing anddesignD.Staton,E.Chong,S.PickeringandA.Boglietti
Volume110 HighVoltagePowerNetworkConstruction K.Harker
Volume111 EnergyStorageatDifferentVoltageLevels:Technology,integration,and marketaspects A.F.Zobaa,P.F.Ribeiro,S.H.A.AleemandS.N.Afifi(Editors)
Volume112 WirelessPowerTransfer:Theory,TechnologyandApplication N.Shinohara
Volume114 Lightning-InducedEffectsinElectricalandTelecommunicationSystems Y.BabaandV.A.Rakov
Volume115 DCDistributionSystemsandMicrogrids T.Dragi ˇ cevi ´ c,F.Blaabjergand P.Wheeler
Volume116 ModellingandSimulationofHVDCTransmission M.Han(Editor)
Volume117 StructuralControlandFaultDetectionofWindTurbineSystems H.R.Karimi
Volume119 ThermalPowerPlantControlandInstrumentation:Thecontrolofboilers andHRSGs,2nd Edition D.Lindsley,J.GristandD.Parker
Volume120 FaultDiagnosisforRobustInverterPowerDrives A.Ginart(Editor)
Volume121 MonitoringandControlusingSynchrophasorsinPowerSystemswith Renewables I.KamwaandC.Lu(Editors)
Volume123 PowerSystemsElectromagneticTransientsSimulation,2nd Edition N.WatsonandJ.Arrillaga
Volume124 PowerMarketTransformation B.Murray
Volume125 WindEnergyModelingandSimulationVolume1:Atmosphereandplant P.Veers(Editor)
Volume126 DiagnosisandFaultToleranceofElectricalMachines,PowerElectronics andDrives A.J.M.Cardoso
Volume128 CharacterizationofWideBandgapPowerSemiconductorDevices F.Wang, Z.ZhangandE.A.Jones
Volume129 RenewableEnergyfromtheOceans:Fromwave,tidalandgradient systemstooffshorewindandsolar D.CoiroandT.Sant(Editors)
Volume130 WindandSolarBasedEnergySystemsforCommunities R.Carriveauand D.S-K.Ting(Editors)
Volume131 MetaheuristicOptimizationinPowerEngineering J.Radosavljevi ´ c
Volume132 PowerLineCommunicationSystemsforSmartGrids I.R.SCasellaand A.Anpalagan
Volume134 HydrogenPassivationandLaserDopingforSiliconSolarCells B.Hallam andC.Chan(Editors)
Volume139 Variability,ScalabilityandStabilityofMicrogrids S.M.Muyeen,S.M.Islam andF.Blaabjerg(Editors)
Volume143 MediumVoltageDCSystemArchitectures B.GraingerandR.D.Doncker (Editors)
Volume145 ConditionMonitoringofRotatingElectricalMachines P.Tavner,L.Ran, C.Crabtree
Volume146 EnergyStorageforPowerSystems,3rd Edition A.G.Ter-Gazarian
Volume147 DistributionSystemsAnalysisandAutomation2nd Edition J.Gers
Volume151 SiCPowerModuleDesign:Performance,robustnessandreliability A.CastellazziandA.Irace(Editors)
Volume152 PowerElectronicDevices:Applications,failuremechanismsand reliability FIannuzzo(Editor)
Volume153 SignalProcessingforFaultDetectionandDiagnosisinElectricMachines andSystems M.Benbouzid(Editor)
Volume155 EnergyGenerationandEfficiencyTechnologiesforGreenResidential Buildings D.TingandR.Carriveau(Editors)
Volume156 Lithium-ionBatteriesEnabledbySiliconAnodes C.BanandK.Xu(Editors)
Volume157 ElectricalSteels,2Volumes A.Moses,K.Jenkins,PhilipAndersonand H.Stanbury
Volume158 AdvancedDielectricMaterialsforElectrostaticCapacitors QLi(Editor)
Volume159 TransformingtheGridTowardsFullyRenewableEnergy O.Probst, S.CastellanosandR.Palacios(Editors)
Volume160 MicrogridsforRuralAreas:Researchandcasestudies R.K.Chauhan, K.ChauhanandS.N.Singh(Editors)
Volume161 ArtificialIntelligenceforSmarterPowerSystems:FuzzyLogicandNeural Networks M.G.Simoes
Volume166 AdvancedCharacterizationofThinFilmSolarCells N.HaegelandMAlJassim(Editors)
Volume167 PowerGridswithRenewableEnergy Storage,integrationanddigitalization A.A.SallamandB.OMP.Malik
Volume169 SmallWindandHydrokineticTurbines P.Clausen,J.WhaleandD.Wood (Editors)
Volume170 ReliabilityofPowerElectronicsConvertersforSolarPhotovoltaic Applications F.Blaabjerg,A.lHaque,H.Wang,Z.AbdinJafferyandY.Yang (Editors)
Volume171 Utility-scaleWindTurbinesandWindFarms A.Vasel-Be-Haghand D.S.-K.Ting
Volume172 LightinginteractionwithPowerSystems,2volumes A.Piantini(Editor)
Volume174 SiliconSolarCellMetallizationandModuleTechnology T.Dullweber (Editor)
Volume180 ProtectionofElectricityDistributionNetworks,4th Edition J.Gersand E.Holmes
Volume182 SurgeProtectionforLowVoltageSystems A.Rousseau(Editor)
Volume184 CompressedAirEnergyStorage:Types,systemsandapplications D.Ting andJ.Stagner
Volume186 SynchronousReluctanceMachines:Analysis,optimizationand applications N.Bianchi,C.BabettoandG.Bacco
Volume191 ElectricFuses:Fundamentalsandnewapplications4th Edition N.Nurse, A.WrightandP.G.Newbery
Volume193 OverheadElectricPowerLines:Theoryandpractice S.Chattopadhyay andA.Das
Volume194 OffshoreWindPowerReliability,availabilityandmaintenance,2nd edition P.Tavner
Volume198 BatteryManagementSystemsandInductiveBalancing A.VandenBossche andA.FarzanMoghaddam
Volume199 ModelPredictiveControlforMicrogrids:Frompowerelectronic converterstoenergymanagement J.Hu,J.M.GuerreroandS.Islam
Volume204 ElectromagneticTransientsinLargeHVCableNetworks:Modelingand calculations Ametani,Xue,OhnoandKhalilnezhad
Volume208 NanogridsandPicogridsandtheirIntegrationwithElectricVehicles S.Chattopadhyay
Volume212 BatteryStateEstimation:MethodsandModels S.Wang
Volume215 IndustrialDemandResponse:Methods,bestpractices,casestudies,and applications H.H.Alhelou,A.Moreno-Mun ˜ ozandP.Siano(Editors)
Volume225 Fusion-FissionHybridNuclearReactors:Forenhancednuclearfuel utilizationandradioactivewastereduction W.M.Stacey
Volume905 Powersystemprotection,4volumes
This page intentionally left blank
ElectricFuses
Fundamentalsandnewapplications
4thEdition
NigelP.M.Nurse,ArthurWrightandP.GordonNewbery
TheInstitutionofEngineeringandTechnology
PublishedbyTheInstitutionofEngineeringandTechnology,London,UnitedKingdom
TheInstitutionofEngineeringandTechnologyisregisteredasaCharityinEngland& Wales(no.211014)andScotland(no.SC038698).
† TheInstitutionofEngineeringandTechnology2022
Firstpublished1982
SecondEdition1995
ThirdEdition2004
FourthEdition2022
ThispublicationiscopyrightundertheBerneConventionandtheUniversalCopyright Convention.Allrightsreserved.Apartfromanyfairdealingforthepurposesofresearch orprivatestudy,orcriticismorreview,aspermittedundertheCopyright,Designsand PatentsAct1988,thispublicationmaybereproduced,storedortransmitted,inany formorbyanymeans,onlywiththepriorpermissioninwritingofthepublishers,orin thecaseofreprographicreproductioninaccordancewiththetermsoflicencesissued bytheCopyrightLicensingAgency.Enquiriesconcerningreproductionoutsidethose termsshouldbesenttothepublisherattheundermentionedaddress:
TheInstitutionofEngineeringandTechnology FuturesPlace KingsWay,Stevenage Hertfordshire,SG12UA,UnitedKingdom
www.theiet.org
Whiletheauthorsandpublisherbelievethattheinformationandguidancegiveninthis workarecorrect,allpartiesmustrelyupontheirownskillandjudgementwhenmaking useofthem.Neithertheauthornorpublisherassumesanyliabilitytoanyoneforany lossordamagecausedbyanyerrororomissioninthework,whethersuchanerroror omissionistheresultofnegligenceoranyothercause.Anyandallsuchliabilityis disclaimed.
Themoralrightsoftheauthortobeidentifiedasauthorofthisworkhavebeen assertedbyhiminaccordancewiththeCopyright,DesignsandPatentsAct1988.
BritishLibraryCataloguinginPublicationData
AcataloguerecordforthisproductisavailablefromtheBritishLibrary
ISBN978-1-83953-408-9(hardback)
ISBN978-1-83953-409-6(PDF)
TypesetinIndiabyMPS
PrintedintheUKbyCPIGroup(UK)Ltd,Croydon
Abouttheauthorsxv
Prefacexvii
Acknowledgementsxix Obituriesxxi
Listofprincipalsymbolsxxiii
1Introduction1
1.1Historyoffusedevelopment1
1.2Basicrequirements9
1.3Fusetypesandconstructions11
1.3.1Classifications11
1.3.2Basicconstructions11
1.3.3‘Resettablefuses’andfaultlimiters14
1.3.4Theantifuse15
1.4Worldproduction15
2Pre-arcingbehaviourofcartridgefuselinks17
2.1Generalbehaviour17
2.1.1Clearanceofveryhighcurrents19
2.1.2Clearanceofhighcurrents22
2.1.3Behaviouratintermediatecurrentlevels24
2.1.4Behaviouratcurrentsneartheminimumfusinglevel25
2.1.5Mathematicalandexperimentalstudies28
2.2Controloftime/currentcharacteristics33
2.3M-effect34
2.3.1Oxidation38
2.4Skinandproximityeffects39
2.5Advancesinmodelling41
3Arcingbehaviourofcartridgefuselinks45
3.1Basicconditionsduringthearcingperiod45 3.2Arcmodel48
3.2.1Cathode-fallregion49
3.2.2Anode-fallregion49
3.3Positivecolumn49
3.3.1Lengthofapositivecolumn49
Contents
x Electricfuses:fundamentalsandnewapplications
3.3.2Cross-sectionalareaofapositivecolumn53
3.3.3Electricalconductivityofapositivecolumn54
3.4Completemathematicalmodel57
4Constructionsandtypesoflow-voltagefuses63
4.1Cartridgefuses64
4.1.1Fuselinkelements64
4.1.2Furtherdetailsonselectionofelementmaterials67
4.1.3Fuselinkbodies69
4.1.4Fillingmaterial69
4.1.5Industrialfuses69
4.1.6Domesticfuses78
4.1.7Fusesfortheprotectionofcircuitscontainingsemiconductor devices80
4.1.8Othertypes84
4.2Semi-enclosedfuses85
4.3ContinentalEuropeanfuses85
4.3.1Blade-contact-typefuses86
4.3.2End-contactorscrew-typefuses91
4.3.3Cylindrical-cap-contactfuses93
4.3.4Semiconductorfuses95
4.4NorthAmericanfuses96
4.4.1Industrialfuses96
4.4.2Domesticfuses102
4.4.3Semiconductorfuses103
4.5Fusesfortelecommunicationpowersystems104
4.6Fusesforrailwayapplications105
4.7Fuseforphotovoltaic(solarpower)systems108
4.8Fusesforbatteryenergystoragesystems111
5Constructionsandtypesofhigh-voltagefuses113
5.1Non-current-limitingfuselinks113
5.1.1Expulsionfuses114
5.1.2Liquidfuses116
5.2Current-limitingfuselinks118
5.2.1ConstructionsofBackUporpartial-rangefuselinks118
5.2.2Current-interruptingabilitiesandcategoriesoffuselinks124
5.2.3Full-Rangefuselinks127
5.3ContinentalEuropeanpractice128
5.4NorthAmericanpractice130
5.4.1Current-limitingfuses131
5.4.2Non-current-limitingfuses131
6Constructionsofminiature,plugandothersmallfuses137
6.1Miniaturefuses137
6.1.1Cartridgefuselinks138
6.1.2Subminiaturefuses145
6.1.3Universalmodularfuselinks146
6.2Domesticplugfuses150
6.3Automotivefuses151
7Applicationoffuses155
7.1Generalaimsandconsiderations155
7.1.1Time/currentrelationships156
7.1.2 I2t 158
7.1.3Virtualtime159
7.1.4Publishedtime/currentcharacteristics160
7.1.5Cut-offcharacteristics161
7.1.6Operatingfrequency161
7.1.7ApplicationoffusestoDCcircuits162
7.2Discriminationandco-ordination164
7.2.1Networksprotectedbyfuses165
7.2.2Networksprotectedbyfusesanddevicesofothertypes166
7.2.3Co-ordinationbetweenacurrent-limitingfuseandadirectly associateddeviceoflowerbreakingcapacity167
7.3Protectionofcables168
7.4Protectionofmotors172
7.4.1Protectionofsoftstarters175
7.5Protectionofpowertransformers176
7.6Protectionofvoltagetransformers183
7.7Protectionofcapacitors184
7.8Protectionofsemiconductordevices189
7.8.1Protectionrequirements189
7.8.2Basicprotectivearrangements191
7.8.3Co-ordinationoffuselinksandsemiconductordevices193
7.8.4Cyclicloadingofsemiconductorfuselinks197
7.8.5Applicationoffuselinkstoequipmentincorporating semiconductordevices199
7.8.6ProtectionofDCthyristordrives204
7.8.7Protectionofinverters208
7.8.8Protectionofpowertransistors209
7.8.9Combinationofrectifierandinverter212
7.8.10Situationswheretherearehighsurgecurrents ofshortduration213
7.8.11Specialapplications214
7.9Protectionagainstelectricshock215
7.9.1Protectionagainstdirectcontact215
7.9.2Protectionagainstindirectcontact215
7.10Arcflash217
7.11Powerquality219
Contents xi
7.12Protectionofphotovoltaic(PV)systems220
7.13Protectionofbatteryenergystoragesystems228
8Internationalandnationalstandards231
8.1Contentsofstandards231
8.1.1Scope232
8.1.2Normativereferences232
8.1.3Definitions233
8.1.4Standardconditionsofoperation233
8.1.5Ratingsandcharacteristics234
8.1.6Markings239
8.1.7Typetests240
8.1.8Dimensions246
8.1.9Applicationguides246
8.2IECfusestandards252
8.2.1Low-voltagefuses252
8.2.2High-voltagefuses253
8.2.3Miniaturefuses254
8.2.4Temperaturerise254
8.3Europeanstandards254
8.3.1Britishstandards255
8.3.2Othernationalstandards256
8.4NorthAmericanstandards256
8.4.1Low-voltageandminiaturefuses256
8.4.2High-voltagefuses257
8.5Approvalsprocedure257
9Manufacture,qualityassuranceandinspection261
9.1Qualityassurance261
9.2Designandmanufacturingcontrol262
9.3Purchasedmaterialandcomponents263
9.3.1Bodies264
9.3.2Endcaps266
9.3.3Elementmaterial266
9.3.4Granularfillingmaterial266
9.3.5Machinedpartsforstrikerassemblies267
9.3.6Componentsandothermaterials267
9.3.7Calibration267
9.4In-processinspection267
9.4.1Productionoffuselinkelements267
9.4.2Windingofhigh-voltage-fuselinkelements268
9.4.3Fuselinkassembly268
9.4.4Strikerassemblies268
9.4.5In-processfinalinspection269
9.4.6Dimensionalcheck269
xii
Electricfuses:fundamentalsandnewapplications
9.4.7X-rayexamination269
9.4.8Resistancemeasurement269
9.5Otherfuseparts269
10Fuserecycling–evenafteroperationfusesarestilluseful271 References273 Glossaryofterms279 Bibliography283 Index285
Contents
xiii
This page intentionally left blank
Abouttheauthors
NigelP.M.Nurse wasaseniorengineeratEatonElectricalProductsLtd,UK.He hasbeeninvolvedinthefuselinkindustrysince1976.Nigelworkedcloselywith GordonNewberyformuchofhiscareer,andhisthesiswassupervisedbythelate Prof.A.Wright.Nigelhasbeendirectlyinvolvedwiththedesign,manufactureand applicationsoffuselinksforover40yearsandisaco-authororauthorofanumber ofpapers.
ArthurWright wasaprofessorofelectricalengineeringattheUniversityof Nottingham.Hisspecificexpertisewasinthefieldsofprotectiverelaying andfuses.
P.GordonNewbery wasinvolvedwiththefuseindustryforover40years.Hewas technicaldirectorforBrush/HawkerFusegearandsubsequentlyfortheBussmann DivisionofCooperIndustriesinEuropeandwasinvolvedwithfusestandardsin Britishandinternationalcommittees.
This page intentionally left blank
Preface
Fuseshavebeenproducedforover100yearsandtherearenowanextremelylarge numberinusethroughouttheworld.Theyperformthevitaldutyofprotecting equipmentandelectricalnetworksandensurethattheeffectsoffaults,which inevitablyoccur,arelimitedandthatthecontinuityofsupplytoconsumersis maintainedatahighlevel.
Notonlyelectricalengineers,butnearlyallmembersofthepublicareawareof theexistenceoffusesandthegeneralimpressionisthattheyaresimpledevicesin allrespects.Whileitistruethattheirconstructionisnotcomplex,theymustbe designedandmanufacturedwithgreatcaretoensurethattheywillperformas required.Surprisingly,thearcingprocesswhichoccurswhentheyareinterrupting currentisstillnotfullyunderstood.Researchiscontinuingonthistopicwiththe objectofproducingfusescapableofmeetingtheever-increasingperformance demandsmadeonthem.Inthisconnection,theadventandrapidgrowthofsemiconductordevices,withtheirlimitedoverloadcapacities,hasintroducedparticularlystringentrequirements.
Theauthorsconsiderthesubjecttobeofgreatimportanceandinterestand thereforedecidedtoproducethisbookwhichattemptstooutlinethehistoryand earlydevelopmentoffuses.Itthendescribesrecenttheoreticalinvestigationsofthe current-interruptionprocessbeforedescribingtheconstructionsofthewiderange offuseswhicharecurrentlyproducedthroughouttheworld.Thelaterchaptersdeal withapplicationrequirements,thevariousnationalandinternationalstandardswith whichfusesmustcomplyand,finally,thequality-assuranceandinspectionprocedureswhichareadoptedbymanufacturersaredescribed.
ThisFourthEditionincludessalientaspectsthathavearisensincethepublicationoftheThirdEditionin2004,including:
● Developmentsinmodelling.
● Fusesfortheprotectionofphotovoltaicsystems
● Fusesfortheprotectionofbatteryenergystoragesystems
● Fusesfortheprotectionofelectricvehicles
● Anupdateonnationalandinternationalstandards
● Additionalchallengesofmeetingautomotivequalitysystems
This page intentionally left blank
Acknowledgements
InacknowledgementoftheworkofNewberyandWright,wherepossibleIhave endeavoredtoleaveasmuchofthepreviousthreeeditionsofelectricfuses untouched,unlessspecificcorrectionsoradditionswererequiredtotheirtext.
ForthisFourthEdition,NigelNursewishestorecordhisthankstothefollowingfuseexperts,fortheircontributions:
HerbertBessei
RussellBrown
Jean-FrancoisDePalma
JohnLeach
HaroldHandcock
StephenLake
Healsowishestothankthefollowingcompaniesfortheirhelpwiththe additionalillustrations:
BrecknellWillis,WabtecCompany
EatonElectricalProductsLtd
Mersen
NH-HHRecycling
ThanksareextendedtoEatonElectricalProductsLtdforthefacilitiesmade availableduringthepreparationofthefourthedition.
TheauthorthankstheInternationalElectrotechnicalCommission(IEC)for permissiontoreproduceInformationfromitsInternationalStandards.Allsuch extractsarecopyrightofIEC,Geneva,Switzerland.Allrightsreserved.Further informationontheIECisavailablefromwww.iec.ch.IEChasnoresponsibilityfor theplacementandcontextinwhichtheextractsandcontentsarereproducedbythe author,norisIECinanywayresponsiblefortheothercontentoraccuracytherein.
Itshouldbealsorecordedthatthefollowingcontributedtothethirdedition:
J.Bender
R.Douglas
D.Giblin
J.Gould
V.Granville
P.M.McEwan
T.W.Mennell
R.Mollett
P.Reinhold
P.Rosen
V.Saporita
T.J.Stack
R.Wilkins
Othercontributorstothefirstandsecondeditions
D.Watson
P.Rosen
J.Gibson
J.G.Leach
K.J.Beaumont
A.F.Howe
andthemanycompanieswhosuppliedillustrationsoverthepreviouseditions:CooperBussmann,SchneiderElectric,BrushIndustrialControlsLtd,Hawker SwitchgearLtd,GECHenleyLtd,InternationalRectifierLtd,K.E.BeswickLtd, BrushElectricalmachinesLtdBrushFusegearLtd,BrushPowerEquipmentLtd, BrushSwitchgearLtd,CromptonParkinsonLtd,MidlandElectricManufacturing CompanyLtd,SouthWalesSwitchgearLtd.(Namesasatthetimeofcontribution)
AlsonotedareAvrilBurtonforherassistancewitheditions2and3andMiss S.E.Taylorwhotypedthemanuscript,andMrJ.Taylorwhopreparedmanyofthe illustrations,foredition1.
June2022
N.P.M.Nurse
xx
Electricfuses:fundamentalsandnewapplications
Obituries
ArthurWrightwasaleadingauthorityontheprotectionofelectricalpowersystems andespeciallycurrenttransformersandfuses.Hepassedawayin1996aged73.His lectureswereenlightening,literally.Athisinaugurallecture,hehadarcsleaping acrosshigh-voltageinsulators,giganticdemonstrationfusesoperatingandlarge electricmotorsbraking,reversingandacceleratingveryrapidly.Alaypreacherfor manyyears,heevenmanagedtoincorporateelectromagneticdemonstrationsinto hissermons.
InArthur’searlydaysattheUniversityofNottingham,therewerenoinduction coursesfornewlecturersand‘mentors’withwhomtodiscussproblems.Arthur filledthisgapwillingly,applyinghiscommonsenseandgoodhumourtoinspire youngacademics.Heprovidedpracticalhelponhowtoimprovelectures,guidance onresearch,alongwithimportantadviceonhowtobuyahouseandbringupyoung children.
Belyinghisquietandunassumingmanner,hewasadedicatedpersonwith resolutedetermination.Hehadtheenviableabilitytocommunicateandobtainthe respectofpeopleatalllevelsandhisendeavoursseldom,ifever,ledtofrictionor badfeeling.Hisoutstandinggiftwasanenthusiasmforlifeandpeopleingeneral andhisabilitytorelatetoeverybody.WithJoantowhomhewashappilymarried for49years,hesharedaloveofmusicandwiththeirtwochildrenBarryandSuehe enjoyedwatchinghisfavouritefootballteams,SunderlandandNottinghamForest.
AlanHoweandGordonNewbery
PercyGordonNewbery1940–2009
AftergraduatingfromBathUniversity,GordonjoinedtheBrushcompaniesin Loughboroughrapidlyfindinganicherolewiththefusedepartment.Gordonwas instrumentalinsettingupalong-termjointresearchprogrammeintoelectricfuses withtheUniversityofNottinghamstartingin1966andwhichcontinuedintothe 1990s,aprogrammethatresultedinmorethansevenhigherdegrees.
AtBrushFusegearbecameoneoftheyoungesttechnicaldirectorswithinthe HawkerSiddelygroup,leadingtheengineeringteamfromthe1970suntilhis retirement,heledhisteamtodevelopclassleadingproductsthatenabledBrushto becomethelargestfusemanufacturerintheUKandonethatwaswellrespected worldwide.
GordonwasinvolvedwithStandardsbothintheUKandinternationallyfrom hisearlydayswithBrushandhispassionforfusesensuredfuseswerealways consideredthemostreliableformofprotectionavailableandthattheyweregiven thesameprominenceininstallationregulationsasMCBsandotherprotective devices.AfterhisformalretirementhemaintainedhisinvolvementwithBEAMA, BSIandIECcommittees.Oftenbeingchairmenorsecretaryorconveneratnational andinternationallevelsatthesametime.Hisdedicationwasfundamentaltothe standardswehavenow.HissenseofhumourattheIECmeetingswaslegendary, hisdepthofknowledgewillbedearlymissed.
NigelNurseandAndrewMurray
xxii Electricfuses:fundamentalsandnewapplications
Listofprincipalsymbols
Aa ¼ cross-sectionalareaofarccolumn
Ae ¼ cross-sectionalareaofelectrode
C ¼ capacitance
D ¼ densityofelectrodematerial
da ¼ diameterofarccolumn
Ea ¼ energyinputtocolumnin dt seconds
EJ ¼ ionisationenergyofanatomoftheelementmaterial
es ¼ sourceEMF
i ¼ instantaneouscurrent
Km,n, Kmþ1,n etc. ¼ thermalconductivitiesofsubvolumes m, n and m þ 1, n etc.
l ¼ lengthofarc
la ¼ lengthofarccolumn
Lc ¼ circuitinductance
Lf ¼ latentheatoffusionofelementmaterial
Lv ¼ latentheatofvaporisation
mt ¼ totalelectrodemasswhichismelted
mv ¼ massofelectrodewhichisvaporised
Na ¼ numberofatomsevaporatedfromtheelectrodesin dt seconds
Nd ¼ numberofatomsscatteredoutofarcin dt seconds
Ne ¼ numberofelectronsscatteredoutofarcin dt seconds
Ng ¼ numberofatomspergramofelectrodematerial
n ¼ numberofnotchesinelement
na ¼ atomicdensity
ne ¼ electrondensity
Ra ¼ resistanceofarccolumn
Ram ¼ elementresistanceatambienttemperature
Rc ¼ resistanceofcircuit
Rf ¼ resistanceoffuse
t ¼ time
ta ¼ arcingtime
v ¼ instantaneousvoltage
va ¼ voltagealongarccolumn
Vaf ¼ voltageassociatedwithanodefall
Vcf ¼ voltageassociatedwiththecathodefall
VT ¼ voltageassociatedwiththethermalenergyoftheelectronswhichenter theanode
Vwf ¼ voltageassociatedwiththeworkfunctionoftheelementmaterial
VJ ¼ vapourjetvelocity
vola ¼ volumeofthearccolumn
X ¼ ionisationfraction
a ¼ resistancetemperaturecoefficientofelement
dt ¼ timeintervalusedforcomputations
Chc ¼ heatenergyconductedtoasubvolumeintime Ct
Chg ¼ heatenergygeneratedinasubvolumeintime Ct
Chl ¼ heatenergylostfromasubvolumeintime Ct
Chs ¼ heatenergystoredinasubvolumeintime Ct
qa ¼ temperatureofarccolumn
qm,n, qm,nþ1 etc. ¼ temperaturesaboveambientatthecentresofsubvolumes m, n and m, n þ 1etc.
l ¼ specificheat
s ¼ electricalconductivityofthecolumn
Subscripts
1 ¼ quantitiesatthebeginningofatimeinterval dt
2 ¼ quantitiesattheendofatimeinterval dt
xxiv Electricfuses:fundamentalsandnewapplications
Chapter1
Introduction
Fusesareamongthebestknownofelectricaldevicesbecausemostofushavequite largenumbersoftheminourhomesand,unlessweareextremelyfortunate,weare madeawareoftheirpresencefromtimetotimewhenonemustbereplacedbecause ithasblownor,tousetheofficialterm,operated.Theyarebasicallysimpleand relativelycheapdevices,althoughtheirbehaviourissomewhatmorecomplexthan maybegenerallyrealised.
Theunderlyingprincipleassociatedwithfusesisthatarelativelyshortpieceof conductingmaterial,withacross-sectionalareainsufficienttocarrycurrentsquite ashighasthosewhichmaybepermittedtoflowintheprotectedcircuit,issacrificed,whennecessary,topreventhealthypartsofthecircuitbeingdamagedandto limitthedamagetofaultysectionsoritemstothelowestpossiblelevel.Asan example,afuseelement,afewcentimetreslongwithaparticularcross-sectional area,couldbeusedtoprotectanelectricalmachinewindingcontainingaconsiderablelengthofconductor,maybekilometres,ofacross-sectionalareaslightly greaterthanthatofthefuseelement.Inthiscase,thevolumeofconducting materialtobesacrificedintheeventofafaultwouldonlybeatinyfractionofthat beingprotectedandthecostoftheprotectionwouldclearlybeacceptable.
Fusesincorporateoneormorecurrent-carryingelements,dependingontheir currentratings,andmeltingofthese,followedbyarcing,occurswhenexcessive over-currentsflowthroughthem.Theycanbedesignedtointerruptsafelythevery highestfaultcurrentsthatmaybeencounteredinservice,and,becauseoftherapidity oftheiroperationinthesecircumstances,theylimittheenergydissipatedduringfault periods.Thisenablesthefusestobeofrelativelysmalloveralldimensionsandmay alsoleadtoeconomiesinthecostandsizeoftheprotectedequipment.
Becauseoftheaboveadvantageousfeatures,fuseshavebeenandareusedina widevarietyofapplications,anditappearsthatthedemandforthemwillcontinueat ahighlevelinthefuture.Theywereundoubtedlyincorporatedintheearliestelectric circuitsinwhichthesourcepowerandvalueoftheequipmentweresignificant.
1.1Historyoffusedevelopment
SincetheSecondEdition,anearlierreferencetofuseshascometolightin1774by EdwardNairne.ThiswasintheeraofelectrostaticelectricityandNairnewas tryingtosafelydischargeLeydenbottles(capacitors)usingwireswithlength
relatedtothestoredenergy,actinglikeresistorsbutwhenthedischargecurrents weretoohigh,thewireactedlikeafuse,disintegratingintosmallballs(unduloids).
AnearlyreferencetofusesoccurredduringthediscussionfollowingthepresentationofapaperbyA.C.Cockburn[1]totheSocietyofTelegraphEngineersin 1887whenW.H.Preecestatedthatplatinumwireshadbeenusedasfusesto protectsubmarinecablessince1864,andSirDavidSalomonsreferredtotheuseof fusesin1874.
Aconsiderablenumberoffusesmusthavebeeninuseby1879,andpresumablythesimplewireconstructionwasnoteventhenadequateforsomeapplicationsbecauseinthatyear,Prof.S.P.Thompsonproducedwhathedescribedas animprovedformoffuseorcut-out.Itconsistedoftwoironwiresconnected togetherbyametallicball,asshowninFigure1.1.Itwasstatedthattheballcould beanalloyofleadandtinorsomeotherconductingmaterialoflowmeltingpoint. Whenasufficientlyhighcurrentispassedthroughthefuseforalongenough period,meltingoftheballoccurredanditfell,allowingthewirestoswingapart andbreakthecircuit.Itshouldberememberedthatmostcircuitsinuseuptoabout 1890carrieddirectcurrentsand,inthesecircumstances,thesuddenseparating actionwouldundoubtedlybeneededtoachievearcextinction.
AvariationonProf.Thompson’sdesignwaspatentedin1883byC.V.Boys andH.H.Cunyngham.Intheirarrangement,thecurrentflowedthroughtwoleaf springswhichweresolderedtogetherattheirinnertips,asshowninFigure1.2. Aboveaparticularcurrent,thesoldermeltedandallowedthestripstoflexin oppositedirections,thusgivingasuddenbreak.Otherphysicalarrangementsbased onthisprinciplewereproduced,onebeingattributedtoSirW.Thomson.
DemonstrationsofincandescentfilamentlampshadbeengiveninBritainby J.Swan(latertobecomeSirJosephSwan)in1878,andalmostsimultaneously byT.A.EdisonintheUSA.Theproductionoftheselampswasstartedshortly afterwardsandthiscausedatremendousdemandforelectriclightinginpublicand privatebuildings.Initialinstallationsincludedtheirowngeneratingplants,but networkssuppliedfromsmallcentralstationsweresooninuse.
Figure1.1FusedevelopedbyProf.S.P.Thompson Figure1.2FusepatentedbyBoysandCunyngham
2 Electricfuses:fundamentalsandnewapplications
Interestingdetailedinformationaboutearlyinstallationsisgiveninletters writtenbyJ.H.HolmesandColonelR.E.CromptontoH.W.Clothierin1932. Excerptsfromtheseletters,whichwereincludedinClothier’sbookentitled SwitchgearStages [2],arereproducedbelow.Theyclearlyindicatethatthereis doubtabouttheidentityofthepersonwhofirstintroducedfuses.
LetterfromMrJ.H.Holmes:
Regardingtheoriginoffuses,Ihavealwaysbeenuncertainastowhois entitledtothecreditofbeingthefirstinventor,andamoftheopinionthatthisisa veryclearcaseof‘NecessityistheMotherofInvention’.
Ihavebeenlookingupsomerecordsofwhatwasknownaboutfusesinthe early‘eighties’,andinthefirstvolumeof‘ElectricIllumination’,compiledby J.DredgeandpublishedAugust,1882,attheOfficesof‘Engineering’,onpage 630itisstatedthatEdison’sBritishPatentofApril,1881,appearstohavebeenthe firstnotificationofleadsafetywire.ItalsoappearsthatEdison’sdevicewascalled a‘safetyguard’.
IthinkhoweverthatSwanusedadeviceforthesamepurposeandbefore April,1881,because‘Cragside’nearhere,theseatofSirW.G.(afterwardsLord) ArmstrongwaslightedwithSwanlampsbythemiddleofDecember,1880.Swan usedtinfoilforthefuse,andastripofthiswasjammedbetweentwobrassblocks, soastoformpartofthecircuit,byaplugofwoodandlaterofsteatite,andIhave samplesofacombinedswitchandfuse,andafuseonlymadeinthisway,and whichwereinuseatCragside.InaSwanUnitedElectricLightCo’scatalogue dated1883,Ifindsuchfusesillustratedandcalled‘safety-fusingbridges’.
InthedescriptionoftheElectricLighting,ontheSwansystem,oftheSavoy Theatrein‘Engineering’,March3,1882,‘fusiblesafetyshunts’arereferredtoas ‘notintendedsomuchtoguardagainstadangerwhichisnexttoimpossibleto occurinpracticalworking,buttoprotectthelampsthemselvesfromdestruction fromtoopowerfulacurrentbeingtransmittedthroughthem’.ThisseemstoconfirmwhatCampbellSwintonsaysabouttheDrawingOfficeatElswickin1882,* whichyouquote,andInotehealsosaysthatattheParisExhibitionof1881there was‘avastarrayofswitches,fuses,cut-outs,andotherapparatus’. †
*‘Itisperhapsnotgenerallyknownthatfuses,asoriginallyintroducedbySwan,weredesignednotasa safeguardtoprotectthewiresagainstoverloadingonshort-circuits,butinordertopreventthelampsfrom over-running.WhenIwenttotheArmstrongWorksatElswickin1882,partofthedrawingofficehadbeen electricallylightedbytheSwanCompany,andeachincandescentlampwasfittedwithaseparatetinfoilfuse forthispurpose.Theprecautionwas,perhaps,anecessaryone,asthelampsthencost25s.eachandwere veryfragile,whilethearrangementsforkeepingaconstantvoltagewereverycrude’.(CampbellSwinton,at theIEECommemorationMeetings,February1922, IEEJournal,1922,Vol.60,p.494.)
†‘In1881theElectricalExhibitionwasheldinParis,atwhichweregatheredtogether,forthefirst time,amostcomprehensiveselectionofallthewonderfulelectricalinventionsoftheprecedingyears TherewereshownincompetitionthethennewlyinventedincandescentlampsofSwan,Edison,Lane FoxandMaxim,togetherwithavastarrayofswitches,fuses,cut-outs,andotherapparatusthathad thenjustbeendesignedtomeettherequirementsofthenewmethodofbothpublicanddomestic illumination’.(CampbellSwinton,IEECommemorationMeetings,February1922, IEEJournal , 1922,Vol.60,p.494.)
Introduction 3
4 Electricfuses:fundamentalsandnewapplications
InthesameCommemorationNumber,Igiveonpage471,anaccount ‡ ofmy firstexperienceofareallyalarming‘short’,andasMrRaworthatonceproposedto haveafusiblewire,whichwasenclosedinawoodenpillbox,putintothecircuit, Ihavealwaysthoughtofhimasoneoftheinventorsofthe‘fuse’.
Ihaveinmycollectionseveralexamplesofbothtinfoilandleadwirefusesin woodenboxeswhichdatefromtheearly‘eighties’,andtheseIhopetofindroom forintheshowcasewhichistocontainmyoldelectriclampsatthenewMunicipal Museum(NewcastleuponTyne).Iamverybusyatpresentcataloguingandfixing thelampsontheslopingshelfwhichwillcarrythemintheshowcase.
LetterfromColonelR.E.Crompton:
Intheyear1881,myfirmgotadefiniteordertolightacountryhouse,thiswas thehouseofMrJesseCoope,apartnerinthefirmofIndCoopethebrewersof Romford.MrCoopewantedhisnewlybuilthousetobeequippedthroughout electricallyandtomypartnerMrHaroldThomson,§ thesonofthegreatinventor andbrotherofSirCourtauldThomson,mustbegivencreditforaverylargeshare ofthedesignofthefittingsandthegeneralarrangements,whichcommencingat Coope’shousewerecarriedoutinalargenumberofcountryhouses,andsome townhouses.Sothatearlyintheyear1882wewereentrustedbyShawLefevre, thenFirstCommissionerofWorks,totenderforthecompleteelectricalinstallation oftheLawCourtswhichwerenearingcompletion.
TheLawCourtsinstallationwasupwardsof2000Swanlampsandwasfitted witheveryappliancethatwehadfoundnecessaryfordomesticworkandIam practicallycertainthatallthebranchcircuitswerethenprotectedbyfuses,andthat therealinventoroffuseswasHaroldThomson.
AtCoope’shouse,HaroldThomsonhadafewbellhangersashisworkmen. Hethenintroducedlampssuspendedfromtheceilingbytheirownconductors,the wholesystemofcontrollinglightsbyswitchesfixednearthedoorways,ceiling rosesandlastbutnotleastthedividingupofeachinstallationintoanumberof smallcircuitscontrolledbysmallswitchboards.
‡‘Thefirststeamshiptocarryelectricarclampsforinteriorilluminationwasthes.s. CityofBerlin,andthe s.s. CityofRichmond wastheearliestinstanceoftheelectriclightingofavesselbytheincandescent systemandwascompletedinJune,1881.Verysoonafterthisdatethes.s. CityofRome wasfittedwitha verycompleteinstallationbythelateMrJohnS.Raworth,onbehalfofMessrs.SiemensBros.&Co.I joinedhisstaffandassistedwiththework,andwaspresentatthefirsttrials.Irememberonerather alarmingoccurrence.Wedidnotknowmuchaboutfuses,andwhenwestarteduptheplantIwashorrified toseesulphuroussmokefromthevulcanisedrubberonthecables,risingfromthetopofthedadoall aroundthemusicsaloon,andturningtherecentlyfinishedwhite-leadpaintingtoastreakyblack.Irushed offtotheengineroomtogetthecurrentturnedoff(wehadnoswitchesnearer)and,beingthankfulthatwe hadnotsettheshiponfire,webribedthepainterstoworkallnighttoeradicateallevidenceofthemishap’. (Holmes,IEECommemorationMeetings,February1922, IEEJournal,1922,Vol.60,p.471.)
§‘Myfirstpartner,HaroldThomson,wastheinventorordesignerofmostofthecommonappliancesthat wenowuse,asnearlyalltheswitches,plugcontacts,fusearrangements,thegeneralarrangementof switchboards,thesuspensionoflampsbytheirownflexibles,wereworkedoutbyhimandbyMr. Lundberg’.(Crompton,IEECommemorationMeetings,February1922, IEEJournal,1922,Vol.60, p.394.)
Duringtheyearsthatfollowed,sayfrom1881to1885,Cromptonscarriedout averylargenumberofseparateinstallations,tothebestofmybeliefinallofthese thebranchcircuitswereprotectedbyfuses.SothatIfeelpracticallycertainthatthe fuseswereusedtoprotectthebranchcircuitsinthevariousinstallationswhich wereworkedfromtheCentralStationinViennak in1886.{
Severalfactors,includingtheconcernforpublicsafety,thecostandfragilityof thelamps,referredtoearlier,andtheincreasingleveloftheavailablevolt-amperes underfaultconditions,madeevidenttheneedforprotectiveequipment,and,asa result,anumberofworkerssoughttodevelopreliablefuses,therebeingnoother obviousalternativeprotectivedevicesatthattime.
Aconsiderableamountofworkwasdonetoobtainanunderstandingofthe processesinvolvedduringthemeltingoffuseelements.Aparticularlysignificant contributionwasmadebyA.C.Cockburn[1],anddetailsofhisworkaregivenin thepaperreferredtoearlier.Hewascriticalofthephysicalconstructionsand inconsistenciespresentinmanyofthefusesinuseatthetimeandattemptedtoput thedesignoffusesonasoundengineeringbasis.Hestudiedtheeffectoftheheat conductedawayfromfuseelements,totheirterminalsandtheconnectingcables, andrealisedthatthisfactorcouldsignificantlyaffecttheminimumcurrentatwhich aparticularfusewouldmelt.Heinvestigatedthepropertiesofconductorsandtook accountofspecificheat,thermalandelectricalconductivity,andotherparameters inanattempttoselectthematerialswhichshouldprovemostsuitableforuseas fuseelements.Herecognisedthatmaterialswhichoxidisereadilyandsignificantly wouldbeunsuitablebecausethefusecharacteristicswouldchangewithtimeasa result.Havingacquiredagoodunderstandingoffusebehaviour,hedevelopeda fuseinwhichaweightwashungonthewireelementasshowninFigure1.3.Inhis design,unlikethatofProf.Thompson,thecurrentdidnotflowintheweight.He claimedthata‘magicalresult’wasobtained,becausetheweightcausedthewireto breakwhenitbecamesufficientlymoltenandtheperformanceobtainedwasmore consistentthanthatofotherfusesproducedatthetime.Testswhichhedidshowed thatfuseswerenotbeingappliedinaconsistentorscientificmanner,therebeing
k‘TheViennaschemewasremarkableinthatwehadtosupply20000lampsintheatres3/4milefrom thecentralstation.Weuseda5-wiresystem,withabout500voltsacrossthedynamoterminals,the distributionbeingbyfourlargebatteriesofaccumulatorscoupledbetweenthefivewires.TheWillans engineswereof200h.p.eachandwereelectricallygoverned....
AsourworkatViennaextendedtothoseinstallationsattheGrandOperaandothertheatreswehad todevise,forthefirsttime,mostoftheelectricapplianceswhicharestillinuseintheatres.MonierandI workedoutconvenientmethodsofindicatingthecurrentinourfeedersbymeasuringthefallofpotential onaportionofourbus-bars,byusingadelicateD’Arsonvalgalvanometerwithmagneticcontrol:inthis waywewereabletomeasurecurrentsuptoseveralthousandampereswithin1percent.Duringthe progressoftheViennawork,whichwentonfrom1884to1887,weattemptedtocommencehouse-tohouselightinginLondon,butfounditverydifficulttoraisecapitalunderthetermsoftheoriginal ChamberlainAct’.(Crompton,IEECommemorationMeetings,February1922, IEEJournal,1922, Vol.60,p.394.)
{InanotherLetter,Col.CromptonrecallsabadshortonthebigswitchboardattheSchenkenstrasse station,causedbyoneofhisfitters,GeorgeEarthy(whoafterwardsbecameateacherattheBattersea Polytechnic),andpointsoutthatthiswas‘thefirstcentralstationeverbuiltintheworld’.
Introduction
5
