Structural Engineering of Transmission Lines

Contents Foreword xi
Preface xiii
1 Introduction 1
A few definitions 2
Units of measure 3
A comment on knowing 4
The value of curiosity 5
A comment on what drives and rewards you 5
Your power and responsibilities as an engineer 5
For the design and construction engineer 6
For the maintenance and operations engineer 7
Being part of a team 7
Not your grandfather’s transmission line 8
2 A transmission line in an electrical network 11
Why should you care about electricity? 12
Being part of a system 12
Planners and designers 12
Normal and contingency loads 13
Ampacity 15
Impedance and line loadability 17
Power loss 20
Clearances 22
Insulation 24
Corona 27
Audible noise 28
Electric and magnetic fields 29
HVDC lines 30
Features and controlling factors 31
Bibliography 33
3 The nature of wires in spans 35
The catenary and the parabola 35
Slack 39
Ruling span in principle 43
Ruling span in detail 49
Wind and weight spans 59
Measuring sag 61
Sag-tension calculations 63
High-temperature compression in aluminium 78
Rated tensile strength defined 80
Summary of useful equations 83
References 85
4 A transmission line as a structural entity 87
Conductors 87
Conductor selection 107
Structures 116
Insulation 136
Hardware 144
Summary of useful equations 151
References 151
5 Loads and strengths 153
Load sources 155
Summary comments on loads 171
Strengths of materials 172
Blending loads with strengths 178
References 184
6 Fun with cable structures 187
The transmission line catenaries 188
The cross-rope suspension structure 210
King of the highwire 211
A little summary of cable projects 222
References 222
7 Lessons from failures 223
Important understandings 224
Wind events and cascade types 227
Icing events 231
The devilish details and other matters 238
Summary 261
References 262
8 Projects 263
A preface to getting busy 263
The design process 270
Design criteria 272
Design load cases 281
Strengths versus deflection 282
Controlling failure sequence 288
Failure containment 288
Analysis methods 289
Line layout (structure spotting) 291
Presentation of results 294
Optimisation 295
Contracts 295
Contractors, consultants and manufacturers 299
Line ‘life’ after engineering 301
References 302
9 Sustainable development 303
The global view 303
SD within the power delivery industry 305
References 315
10 Further information 317
CIGRE technical brochures 317
Papers by H. Brian White 319
Index 325