Table Of ContentStructural Engineering of
Transmission Lines
Therearereasonableplacesfortransmissionlinesand
thereareusefulbutunreasonableplacesfortransmission
lines.Somearechallengingandfuntoengineerandsome
areyawners.Here’shopingthatsomeofyourdays
requiretacklingtheunreasonableonesbecausethey’re
fun!
CrossingTwinPeaksinBritishColumbiawiththe
Kemano–Kitimattransmissionline,1950s.
(CourtesyofH.BrianWhite)
Structural
Engineering of
Transmission Lines
Peter Catchpole
PEng
with Buck Fife
CoverphotographbyErikRuggeri:CrewliftingthemiddlephasetoCatenary2,
Nebraska,2008
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ProductionEditor:VikarnChowdhary
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IndexcreatedbyPaulineDavies
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Thisbookisdedicatedtotheteachersandmentorsthat
haveinfluencedmywork,mostnotablyH.BrianWhite,
andtotheyoungerengineerswhoshowakeeninterestin
theworkandonwhoseintelligence,curiosityandpursuit
ofexcellencereliesthefutureoftheengineeringof
transmissionlines.
Brian(right)andIconferredattheinitialstagesofseveral
projects.Itwasalwaysuseful
v
Contents Foreword xi
Preface xiii
01 ............................ Introduction 1
Afewdefinitions 2
Unitsofmeasure 3
Acommentonknowing 4
Thevalueofcuriosity 5
Acommentonwhatdrivesandrewardsyou 5
Yourpowerandresponsibilitiesasanengineer 5
Forthedesignandconstructionengineer 6
Forthemaintenanceandoperationsengineer 7
Beingpartofateam 7
Notyourgrandfather’stransmissionline 8
02 ............................ Atransmissionlineinanelectricalnetwork 11
Whyshouldyoucareaboutelectricity? 12
Beingpartofasystem 12
Plannersanddesigners 12
Normalandcontingencyloads 13
Ampacity 15
Impedanceandlineloadability 17
Powerloss 20
Clearances 22
Insulation 24
Corona 27
Audiblenoise 28
Electricandmagneticfields 29
HVDClines 30
Featuresandcontrollingfactors 31
Bibliography 33
03 ............................ Thenatureofwiresinspans 35
Thecatenaryandtheparabola 35
Slack 39
Rulingspaninprinciple 43
Rulingspanindetail 49
Windandweightspans 59
Measuringsag 61
Sag–tensioncalculations 63
High-temperaturecompressioninaluminium 78
Ratedtensilestrengthdefined 80
Summaryofusefulequations 83
References 85
04 ............................ Atransmissionlineasastructuralentity 87
Conductors 87
vii
Conductorselection 107
Structures 116
Insulation 136
Hardware 144
Summaryofusefulequations 151
References 151
05 ............................ Loadsandstrengths 153
Loadsources 155
Summarycommentsonloads 171
Strengthsofmaterials 172
Blendingloadswithstrengths 178
References 184
06 ............................ Funwithcablestructures 187
Thetransmissionlinecatenaries 188
Thecross-ropesuspensionstructure 210
Kingofthehighwire 211
Alittlesummaryofcableprojects 222
References 222
07 ............................ Lessonsfromfailures 223
Importantunderstandings 224
Windeventsandcascadetypes 227
Icingevents 231
Thedevilishdetailsandothermatters 238
Summary 261
Reference 262
08 ............................ Projects 263
Aprefacetogettingbusy 263
Thedesignprocess 270
Designcriteria 272
Designloadcases 281
Strengthsversusdeflection 282
Controllingfailuresequence 288
Failurecontainment 288
Analysismethods 289
Linelayout(structurespotting) 291
Presentationofresults 294
Optimisation 295
Contracts 295
Contractors,consultantsandmanufacturers 299
Line‘life’afterengineering 301
References 302
viii
09 ............................ Sustainabledevelopment 303
Theglobalview 303
SDwithinthepowerdeliveryindustry 305
References 315
10 ............................ Furtherinformation 317
CIGRE´ technicalbrochures 317
PapersbyH.BrianWhite 319
Index 325
ix
