F. Kiessling • P. Nefzger • J.F. Nolasco • U. Kaintzyk
Overhead Power Lines
Planning, Design, Construction
With 402 Figures and 193 Tables
Springer
Contents
1 Overall planning
1.0 Symbols
1.1 Development stages of a transmission project
1.2 Transmission planning
1.2.1 Objective
1.2.2 Planning stages
1.2.3 Planning aspects regarding transmission lines
1.3 Planning methods
1.3.1 Data acquisition and preparation
1.3.2 Formulation and preselection of alternatives
1.3.3 Electrical studies
1.3.4 Economic studies and final evaluation
1.4 Planning criteria
1.4.1 General
1.4.2 Criteria for steady-state conditions
1.4.3 Criteria for temporary and transient conditions
1.5 Evolution and selection of voltage levels
1.5.1 Evolution of transmission voltages
1.5.2 Introduction of transmission voltages
1.6 Conductor selection
1.7 Selection of line configuration
1.8 Direct current transmission
1.8.1 Aspects of DC transmission components
1.8.2 Economic comparison of DC and AC lines
1.8.3 Technical comparison of AC and DC transmission
1.8.4 Practical use of DC transmission
1.9 Transmission with higher order phase lines
1.9.1 Options
1.9.2 Properties of multiple-phase systems
1.9.3 Present experience
1.10 Investments
1.11 Licences and permit procedures
1.12 Underground transmission versus overhead lines
1.12.1 Application and planning aspects
1.12.2 Environmental constraints
1.12.3 Technical limitations
1.12.4 Comparative investments
1.12.5 Perspectives
1.13 Results of overall planning
1.14 References
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2 Electric requirements and design
2.0
Symbols
2.1
Overhead lines as components of electric systems
2.1.1 Surge impedance and surge impedance load (natural power)
2.1.2
Stability
2.1.3 Voltage regulation and maximum permissible losses
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Contents
2.1.4
Capability of a line
2.1.5 Reliability and availability
2.1.6 Reactive power compensation
2.1.7 Power transmitted versus right-of-way width
2.2
Current-related phenomena
2.2.1 Normal and emergency conditions
2.2.2
Ohmic losses
2.2.3 Short circuit condition
2.3
Voltage and current-related phenomena
2.3.1 Introduction
2.3.2 Electrical and magnetic fields
2.3.2.1 Effects on humans and animals
2.3.2.2 Effects on electronic devices
2.3.3 Corona phenomena and related effects
2.3.3.1 General
2.3.3.2 Calculation of voltage gradients on individual conductors
2.3.3.3 Calculation of voltage gradient by approximate formulae
2.3.3.4 Radio noise or radio interference (RI)
2.3.4 Audible noise (AN)
2.3.5 Impact of line design on voltage- and current-depending phenomena . .
2.4
Line performance and insulation requirements
2.4.1 Introduction
2.4.2 Power frequency voltages and temporary overvoltages
2.4.3 Slow-front overvoltages
2.4.4 Fast-front overvoltages
2.4.5 Principles of insulation coordination
2.4.5.1 General principles
2.4.5.2 Insulation design for permanent power frequency voltages
2.4.5.3 Insulation design for slow-front overvoltages
2.4.5.4 Insulation design for fast-front overvoltage
2.4.6 Live-line maintenance
2.5
Clearances
2.5.1 Clearance requirements
2.5.1.1 Types of electrical clearances
2.5.1.2 Calculation of electrical clearances
2.5.1.2.1 Required withstand voltages of air gaps
2.5.1.2.2 Voltages to be considered
2.5.1.2.3 Summary of formulae for electrical clearances
2.5.1.3 Empirical data for clearances
2.5.2 Internal and external clearances
2.5.2.1 Introduction
2.5.2.2 Design principles
2.5.2.3 Load cases for the calculation of clearances
2.5.2.3.1 Maximum conductor temperature at no-wind condition
2.5.2.3.2 Ice load without wind
2.5.2.3.3 Wind load assumptions
2.5.2.4 Insulator and conductor position under wind action
2.5.2.4.1 Definition of wind action
2.5.2.4.2
Calculation of swing angle
2.5.2.4.3 Time distribution of swing angles
2.5.2.4.4 Determination of swing angles by measurements
2.5.2.4.5 Conductor and insulator position according to standards . . . .
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Contents
XIII
2.5.2.5 Midspan clearances
2.5.2.6 Minimum clearances within a span or at a tower
2.5.2.7 Clearances to ground and obstacles
2.5.2.8 Examples
2.5.2.8.1 Electrical clearances for a 110 kV overhead line
2.5.2.8.2 Electrical clearances for a 380 kV overhead line
2.5.2.8.3 Electrical clearances for a 500 kV overhead line
2.5.2.8.4 Clearances to obstacles for line design, empirical approach . . .
2.5.2.8.5 Time distribution of swing angles
2.5.2.8.6 Tower top geometry according to statistic considerations . . . .
2.5.2.8.7 Tower top geometry according to European standards
2.5.2.8.8 Tower top geometry according to Brazilian practice
2.6
References
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3 Electric parameters
3.0
Symbols
3.1
Introduction
3.2
Resistance
3.3
Positive-sequence impedance
3.3.1 Introduction
3.3.2
Inductance and inductive Reactance
3.4
Zero-sequence impedance
3.4.1 Introduction
3.4.2
Simplified approach for the determination of zero-sequence impedances
3.5
Capacitance and capacitive reactance
3.5.1
General considerations
3.5.2
Single-circuit lines
3.5.3 Double-circuit lines
3.6
Admittance
3.7
Electric representation of lines
3.7.1
Goals and basic conditions
3.7.2
Short- and medium-length lines
3.7.3
Long-length transmission lines
3.7.3.1 Representation by exponential functions
3.7.3.2 Representation by hyperbolic functions
3.7.3.3 The equivalent II-circuit of a long line
3.8
References
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4 Lightning protection
4.0
Symbols
4.1
Significance of lightning
4.2
Formation of lightning strokes
4.2.1 Mechanism of lightning discharge
4.2.2 Impulse behaviour of lightning discharges
4.2.3 Electric characteristics of the discharges
4.3
Frequency and intensity of lightning strokes
4.3.1 Keraunic levels and earth flash density
4.3.2
Magnitude of lightning stroke currents
4.3.3
Direct and indirect lightning strokes
4.4
Arrangement and efficiency of earth wires
4.4.1 Theoretical background
4.4.2 Effective shielding by earth wires
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Contents
4.4.3 Surge arresters
4.4.4 Assessment of lightning performance of overhead lines
4.5
Earthing in view of lightning protection
4.5.1 Significance of earthing for lightning protection
4.5.2 Surge impedance of earthing systems
4.6
References
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5 Earthing
115
5.0
Symbols
115
5.1
Purpose of earthing
116
5.2
Definitions and basic principles
117
5.3
Requirements
118
5.3.1
Standards
118
5.3.2
Safety of persons
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5.3.3 Thermal short-circuit strength
119
5.3.4
Mechanical strength and corrosion resistance
119
5.3.5
Currents to be considered
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5.4
Earthing for personal safety purposes
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5.5
Operational earthing
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5.6
Lightning protection earthing
124
5.7
Rating for short-term currents
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5.8
Soil resistivity and conductivity
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5.9
Calculation of earthing resistance
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5.9.1 Spherical electrode
126
5.9.2
Earthing rods
127
5.9.3 Horizontally arranged electrode wires (counterpoises)
129
5.10 Measurements of soil resistivity
130
5.10.1 Basic principles
130
5.10.2 Measuring methods
131
5.11 Measurement of earthing resistance
132
5.12 Earthing resistance in non-homogeneous soils
135
5.12.1 Soil resistivity in a two-layer soil structure
135
5.12.2 Computation of earthing resistance in a two-layer soil structure . . . . 136
5.12.3 Computation of earthing resistance by means of the apparent resistivity 138
5.12.4 Computation of earthing resistance of three-dimensional structures . . 138
5.12.5 Example for computation of earthing resistance
139
5.13 Practical rules for installation of earthing systems
139
5.13.1 Radial and ring-type earthing counterpoises
139
5.13.2 Vertically or obliquely driven earthing rods
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5.13.3 Bonding between earthing electrodes
140
5.13.4 Earthing connections
140
5.14 References
140
6 Requirements on loading and strength
143
6.0
Symbols
143
6.1
Mechanical design of the overhead line system
145
6.1.1
Components and elements of an overhead line
145
6.1.2
Reliability
145
6.1.3 Calculation of reliability
146
6.1.4
Strength coordination and selection of reliability
150
6.1.5 Effect of maximum load intensity on a high number of components . . 152
6.1.6
Use factor and its effect on the design
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Contents
XV
6.2
Strengths of line components and elements
156
6.2.1
Strength limits
156
6.2.2
Rating of individual components and elements
157
6.2.3 Damage and failure limits
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6.3
Wind loads
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6.3.1 Wind measurements
158
6.3.2 Determination of meteorological reference wind velocities
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6.3.2.1 Evaluation of wind measurements
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6.3.2.2 Effect of the terrain roughness
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6.3.2.3 Variation of reference wind velocity with height
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6.3.3 Wind action on line components and elements
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6.4
Ice loads
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6.4.1 Atmospheric icing
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6.4.2 Ice observations and measurements
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6.4.3 Determination of reference ice loads
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6.4.3.1 Basic relations
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6.4.3.2 Evaluation of ice load information
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6.4.3.3 Reference ice load
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6.4.3.4 Loading of supports and load cases
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6.5
Combined wind and ice loads
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6.5.1 Probability of occurrence and combination of parameters
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6.5.2
Determination of design parameters
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6.5.2.1 Ice load
170
6.5.2.2 Wind load
170
6.5.2.3 Effective drag factors and ice densities
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6.5.3 Wind action on the ice covered conductor
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6.6
Climatic loads according to relevant standards
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6.6.1 Standards for overhead power lines
172
6.6.2
Wind loads
172
6.6.2.1 Wind load model according to IEC 60 826
172
6.6.2.2 Wind model according to the European standard EN 50 341-1 . . . 174
6.6.2.3 Wind models according to EN 50 341-3
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6.6.2.4
Comparison of wind load models with measurements
179
6.6.3 Ice loads
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6.6.3.1 Ice load model according to IEC 60 826
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6.6.3.2 Ice load model according to EN 50 341-1
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6.6.3.3 Ice load model according to EN 50 341-3
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6.6.4
Combined wind and ice action
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6.6.4.1 Model according to IEC 60 826
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6.6.4.2 Model according to EN 50 341-1
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6.6.4.3 Combined wind and ice action according to EN 50 341-3
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6.7
Loads at construction, operation and maintenance
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6.7.1 Introduction
185
6.7.2
Requirements according to IEC 60 826
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6.7.3
Requirements according to EN 50 341-1 and EN 50 341-3
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6.8
Failure containment and other special loads
187
6.8.1 Introduction
187
6.8.2
Provisions according to IEC 60 826
187
6.8.3
Provisions according to EN 50 341-1
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6.9
Statistical distributions
188
6.9.1 Introduction
188
6.9.2
Normal distribution (Gaussian distribution)
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XVI
Contents
6.9.3
Log-normal distribution
6.9.4
Gumbel distribution
6.10 References
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7 Selection of conductors
7.0
Symbols
7.1
Conductor types and design
7.1.1 Introduction
7.1.2
Conductor designation
7.1.3 Progress in technical development
7.1.4
Materials
7.1.4.1 Aluminium
7.1.4.2 Aluminium-magnesium-silicon alloys
7.1.4.3 Steel wires
7.1.4.4 Aluminium-clad steel wires
7.1.4.5 Copper and copper alloys
7.1.4.6 Thermal resistant aluminium alloys
7.1.5 Wire testing
7.1.5.1 Introduction
7.1.5.2 Dimensions and surfaces
7.1.5.3 Testing the tensile strength
7.1.5.4 Wrapping and twisting test
7.1.5.5 Testing zinc mass, cladding thickness and uniformity
7.1.5.6 Testing resistivity
7.1.6
Conductors made of wires with the same material
7.1.6.1 All aluminium conductors
7.1.6.2 All aluminium alloy conductors
7.1.6.3 Aluminium-clad steel conductors
7.1.6.4 Copper, copper alloy and steel conductors
7.1.7
Composite conductors
7.1.7.1 Configuration and design
7.1.7.2 Characteristic data
7.1.7.3 Production
7.1.7.4 Joints
7.1.7.5 Shipment
7.1.8 Conductor testing
7.1.8.1 Classification of tests
7.1.8.2 Extent of sample tests
7.1.8.3 Surface condition, dimensions, inertness and mass
7.1.8.4 Stress-strain diagram
7.1.8.5 Tensile breaking strength
7.1.8.6 Test of creep behaviour
7.1.8.7 Testing the tension stringing ability of conductors
7.1.9
Bundle conductors
7.1.10 Special conductor designs
7.1.10.1 Non-standardized conductors made of round wires
7.1.10.2 Conductors for increased operation temperature
7.1.10.3 Conductors with enlarged diameters
7.1.10.4 Conductors with smooth surfaces
7.1.10.5 Compacted conductors
7.1.10.6 Self-damping conductors
7.1.10.7 Vibration resistant conductors
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7.1.10.8 Low noise conductors
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7.1.10.9 Conductors with treated surfaces
223
7.2
Design with regard to current loading
223
7.2.1 Introduction and requirements
223
7.2.2 Principles for determination of conductor temperature
224
7.2.3 Design with regard to current carrying capacity
225
7.2.4 Design with regard to short-circuit current
228
7.2.5 Design based on economic considerations
228
7.2.6
Line capacity as a function of the weather conditions
231
7.3 Design with regard to stresses caused by voltages
232
7.3.1 Introduction and requirements
232
7.3.2 Design with respect to the electric parameters
232
7.3.3 Design with respect to conductor surface gradients and corona effects . 234
7.3.4
Corona losses
234
7.4 Mechanical design of conductors
234
7.4.1 Introduction and requirements
234
7.4.2
Stresses under extreme load conditions
235
7.4.3 Stresses under everyday conditions
236
7.4.4 Impact of the conductor tensile load on line investment
237
7.4.5 Conductor creep
238
7.4.6 Recommendations for selection of conductor tensile stresses
238
7.5 References
238
8 Earth wire selection
243
8.0
Symbols
243
8.1 Types of earth wires
243
8.2
Electric and thermal design
244
8.2.1
Requirements
244
8.2.2 Earth wire design under short-circuit conditions
244
8.2.3 Temperature limits of earth wires in case of short circuits
247
8.2.4
Fault clearing and reclosing operations
247
8.2.5
Examples of earth wire current carrying capacity in case of short circuits248
8.3
Mechanical design
250
8.3.1
Loss of mechanical strength during heating process
250
8.3.2 Establishing tensile stresses and forces
251
8.4
Steps for selection of conventional earth wires
251
8.5
Earth wires comprising optical fibres (OPGW)
252
8.5.1
Generalities and design
252
8.5.2
Installation conditions
254
8.5.3 Accessories
254
8.5.4 Tests
255
8.6
References
255
9 Insulators
9.0
Symbols
9.1 Introduction
9.2
Ceramic insulators
9.2.1 Insulator types and their application
9.2.2 Raw materials
9.2.3 Production
9.3 Glass insulators
9.3.1 Raw materials and production
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Contents
9.3.2
Insulator types and application
266
9.4
Composite insulators
267
9.4.1 Raw materials, design and production
267
9.4.2
Types of composite insulators and their application
268
9.5
Comparison of insulator types
269
9.6
Tests on insulator units
271
9.6.1
Basic information
271
9.6.2
Tests on ceramic and glass insulators
271
9.6.2.1 Type tests
271
9.6.2.2
Sample tests
273
9.6.2.3 Routine tests
275
9.6.3
Tests on composite insulators
276
9.6.3.1 Basic information
276
9.6.3.2 Test of the structural design and type test
276
9.6.3.3 Sample and routine tests
277
9.7
Design of insulator sets
278
9.7.1
Suspension insulator sets
278
9.7.2
Tension insulator sets
281
9.8
Requirements for insulator sets
281
9.8.1 Electric requirements for AC lines
281
9.8.2
Particularities for DC lines
284
9.8.3
Audible noise (AN) performance
286
9.8.4
Mechanical design
287
9.9
Operational performance of insulator strings
287
9.9.1 Introduction
287
9.9.2
Voltage stresses
288
9.9.3
Behaviour of individual insulator types
290
9.9.4
Behaviour under pollution layers
292
9.9.4.1 Formation of pollution layers
292
9.9.4.2 Simulation of pollution layers
292
9.9.4.3 Pollution levels
293
9.9.4.4 Assessment of pollution levels by means of local measurements . . . 293
9.9.4.5 Measures to maintain insulation capacity
294
9.10 Testing of insulator sets
295
9.10.1 Basic information and assumptions
295
9.10.2 Standard atmospheric conditions
295
9.10.3 Artificial rain
295
9.10.4 Testing arrangements
295
9.10.5 Power frequency voltage test
296
9.10.6 Fast-front and slow-front overvoltage tests
296
9.10.7 Power arc behaviour
296
9.10.8 Radio interference strength test
296
9.10.9 Corona onset or extinction voltage test
297
9.11 Example for insulator selection
297
9.12 References
300
10 Overhead line
fittings
10.1 Definitions
10.2 Fittings for conductors
10.2.1 Conductor attachment at suspension insulator sets
10.2.2 Conductor attachments at dead-end terminations
10.2.3 Turn buckles
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10.2.4 Connectors
10.2.5 Spacers for bundle conductors
10.2.6 Vibration dampers for single conductors
10.2.7 Spacer dampers for bundle conductors
10.3 Fittings for insulator sets
10.4 Rating and tests
10.4.1 General
10.4.2 Electric requirements
10.4.3 Mechanical requirements
10.4.4 Corrosion protection
10.4.5 Selection of material
10.4.6 Tests
10.5 References
XIX
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11 Conductor vibrations
321
11.0 Symbols
321
11.1 Overview and types of vibration
322
11.2 Aeolian vibrations
323
11.2.1 Basic physical aspects, mathematic-mechanic model of a line
323
11.2.2 Conductor free-span amplitude
325
11.2.3 Conductor strains and stresses
327
11.2.4 Bending stiffness of a conductor
327
11.2.5 Origin of vibrations
328
11.2.6 Consequences of vibrations
329
11.2.7 Consequences for line design
332
11.2.8 Verification of vibration intensity and effectiveness of damping measures 336
11.2.9 Evaluation of vibration measurements
338
11.3 Subspan oscillations
340
11.3.1 Origin and consequences
340
11.3.2 Remedy measures
341
11.4 Galloping
341
11.4.1 Origin and consequences
341
11.4.2 Remedy measures
343
11.5 Short-circuit oscillations
344
11.5.1 Origin and consequences
344
11.5.2 Remedy measures
344
11.6 References
345
12 Supports
12.0 Symbols
12.1 Support types and their applications
12.1.1 Definitions
12.1.2 Tasks of supports in an overhead line
12.1.2.1 Suspension supports
12.1.2.2 Angle suspension supports
12.1.2.3 Angle supports
12.1.2.4 Strain and angle-strain supports
12.1.2.5 Dead-end supports
12.1.2.6 Special supports
12.1.3 Support design and application
12.1.3.1 Selection of support design
12.1.3.2 Self-supporting lattice steel towers
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Contents
12.1.3.3 Self-supporting steel poles
358
12.1.3.4 Steel-reinforced concrete poles
359
12.1.3.5 Wood poles
360
12.1.3.6 Guyed supports
360
12.1.3.7 Crossarmless supports
360
12.2 Tower top geometry
361
12.2.1 Requirements
361
12.2.2 Electrical clearances according to relevant standards
361
12.2.3 Clearance between conductors
361
12.2.3.1 Equal cross sections, alike materials and equal sags of conductors . 361
12.2.3.2 Conductors with different cross sections, materials or sags
364
12.2.4 Clearances at supports
365
12.3 Basic design requirements
367
12.3.1 Introduction
367
12.3.2 Static design
367
12.3.3 Design values and verification methods
368
12.4 Load cases and partial factors
369
12.4.1 Combination of loads
369
12.4.2 Extreme wind load
370
12.4.3 Wind load at minimum temperature
371
12.4.4 Uniform and unbalanced ice loads without wind
371
12.4.5 Combined wind and ice load
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12.4.6 Construction and maintenance loads
372
12.4.7 Security loads
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12.4.8 Partial factors for actions on supports
373
12.4.9 Partial factors for materials
374
12.5 Lattice steel towers
374
12.5.1 Structural design
374
12.5.1.1 Structural design of members
374
12.5.1.2 Connections
376
12.5.1.3 Walkways
377
12.5.1.4 Production
378
12.5.1.5 Corrosion protection
378
12.5.2 Materials
379
12.5.2.1 Materials for angle sections and plates
379
12.5.2.2 Material for bolts
379
12.5.3 Analysis of member forces
380
12.5.4 Calculation of the member forces at a plane system
381
12.5.4.1 Basic procedure
381
12.5.4.2 Forces in the leg members
381
12.5.4.3 Forces in bracings, loaded by horizontal forces
382
12.5.4.4 Forces in bracings, loaded by asymmetrical vertical forces
383
12.5.4.5 Forces in bracings, loaded by torsional moments
383
12.5.4.6 Total forces in bracings
384
12.5.4.7 Forces in horizontal members at tower waist
384
12.5.4.8 Forces in horizontal bracings within the tower body
385
12.5.4.9 Forces in leg extensions
385
12.5.4.10 Forces in crossarm members
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12.5.5 Analysis of member forces at a three-dimensional system
387
12.5.5.1 Basic approach of the finite element method
387
12.5.5.2 Application to three-dimensional truss structure systems
395
12.5.6 Comparison of computations at plane and three-dimensional systems . 396
Contents
12.5.7 General format of verification of members and connections
12.5.8 Design of compression members
12.5.8.1 Effective cross section properties for compression members
12.5.8.2 Flexural buckling of axially compressed members
12.5.8.3 Flexural torsional buckling of centrally compressed members . . . .
12.5.8.4 Bending and axial compression forces
12.5.9 Design of compound members
L2.5.9.1 Member connected by batten plates
L2.5.9.2 Laced box-type members
12.5.10 Design of tensile-loaded members
L2.5.10.1 Members axially loaded in tension
L2.5.10.2 Axial tensile force and bending
12.5.11 Design of connections
12.5.12 Design for bending due to transverse loads
12.5.13 Design of redundant members
12.5.14 Deformation
12.5.15 Calculation of foundation loads
12.5.16 Application of computer programs for calculation of lattice steel towers
12.5.17 Upgrading the support strength
12.5.18 Example: Static calculation of a 110 kV suspension support
12.5.19 Example: Calculation guy wire and mast loads in a guyed-V tower . .
12.6 Steel poles
12.6.1 Structural design
12.6.2 Analysis of loads
12.6.3 Rating
12.6.4 Example for design of a conical solid-wall steel pole
12.7 Steel-reinforced concrete poles
12.7.1 Selection of cross sections
12.7.2 Spun concrete poles
12.7.3 Vibrated concrete poles
12.7.4 Structural design
12.7.5 Production
12.7.6 Rating
12.7.7 Example for design of a spun concrete pole
12.7.7.1 Basic data
12.7.7.2 Calculation of loads
12.7.7.3 Verification of cross sections
12.8 Wood poles
12.8.1 Application and design
12.8.2 Rating
12.8.3 Treatment of wood poles
12.9 Loading and failing tests
12.9.1 Introduction
12.9.2 Foundations for support under test
12.9.3 Material for the tower under test
12.9.4 Fabrication of the prototype tower under test
12.9.5 Strain measurements
12.9.6 Assembly and erection
12.9.7 Test loads
12.9.8 Load application
12.9.9 Load procedure
12.9.10 Load measurement
XXI
398
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399
406
408
408
408
410
413
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415
415
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418
420
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423
425
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447
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449
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452
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457
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461
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462
462
463
463
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XXII
Contents
12.9.11 Deflections
12.9.12 Acceptance and failures
12.9.13 Destruction test
12.9.14 Disposition of test tower
12.9.15 Test report
12.10 References
464
465
465
465
465
466
13 Foundations
13.0 Symbols
13.1 Requirements and preconditions
13.2 Types of subsoils
13.2.1 Classification of soil
13.2.2 Undisturbed natural soil
13.2.3 Rock
13.2.4 Filled-up soil
13.3 Subsoil investigation
13.3.1 Purpose of subsoil investigation
13.3.2 Methods for obtaining soil samples
13.3.2.1 Type of samples
13.3.2.2 Trial pits
13.3.2.3 Exploratory borings
13.3.2.4 Soil investigation by drilling probes
13.3.3 Probes
13.3.3.1 Types of probes
13.3.3.2 Driven probes
13.3.3.3 Standard penetration test
13.3.3.4 Van-type probes
13.3.3.5 Compression probes
13.3.4 Evaluation of soil investigation
13.3.4.1 Classification and description of soil types
13.3.4.2 Classification of rock
13.3.4.3 Concrete-aggressive water and soils
13.3.4.4 Borehole log
13.3.4.5 Graphical representation
13.4 Design and calculation of foundations
13.4.1 Type of foundation and load
13.4.2 Soil characteristics
13.4.3 Compact foundations
13.4.3.1 Definition
13.4.3.2 Monoblock foundations
13.4.3.3 Monoblock foundations without base enlargement
13.4.3.4 Monoblock foundation with base enlargement
13.4.3.5 Slab foundations
13.4.3.6 Single grillage foundation
13.4.3.7 Single pile foundations
13.4.3.8 Foundation of self-supporting timber poles
13.4.4 Separate foundations
13.4.4.1 Definition
13.4.4.2 Stepped block
foundations
13.4.4.3 Auger-bored and excavated foundations
13.4.4.4 Separate grillage foundations
13.4.4.5 Pile foundations
471
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472
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Contents
XXIII
13.4.4.6 Steel reinforced pad and chimney foundation
13.4.4.7 Foundations in rock
13.4.5 Anchoring of leg member stubs
13.4.6 Foundation for guyed towers
13.4.6.1 Acting loads
13.4.6.2 Central footings
13.4.6.3 Foundations for guy wires
13.4.6.4 Field tests
13.5 Testing of foundations
13.5.1 Definitions and object
13.5.2 Categories of tests
13.5.3 Foundation installation
13.5.4 Testing equipment
13.5.5 Testing procedure
13.5.6 Test evaluation and acceptance criteria
13.5.7 Uplift load tests on construction and test piles
13.6 References
519
521
523
524
524
524
525
526
527
527
527
528
528
529
531
532
534
14 Sag and tension calculations
14.0 Symbols
14.1 Basis
14.2 Sags described by the catenary curve
14.3 Conductor sagging curve as a parabola
. 14.4 Span with differing attachment levels
14.5 Conductor state change equation
;
14.6 Span with concentrated loads
14.7 Span with tension insulator sets at both ends
14.8 Conductor forces and sags in a tensioning section
14.8.1 Introduction
14.8.2 Conductor state in spans with end points movable in line direction . .
14.8.3 Conductor stresses and sags in case of inverted V-insulator sets . . . .
14.8.4 Conductor state change equation for a tensioning section
14.8.5 Computer program for conductor state change in a tensioning section .
14.8.6 Approximate formulae of sags at ice load in one span only
' 14.9 Clearances to ground and to objects
14.9.1 Requirements
14.9.2 Calculation of clearance to ground
14.9.3 Calculation of the clearance to a crossed road
14.9.4 Calculation of clearance to a crossed line
14.10 References
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539
540
540
544
546
546
549
551
553
553
554
556
557
562
562
563
563
564
565
567
570
15 Route selection and detailed line design
15.0 Symbols
15.1 Introduction
15.1.1 Basic information
15.1.2 Preliminary activities
15.
• 2 Route selection and licences
15.2.1 Introduction
15.2.1.1 General aspects and guidelines
15.2.1.2 Alternative line designs
15.2.1.3 Conversion of existing lines
15.2.1.4 Underground transmission
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XXIV
Contents
15.2.2 Regulatory controls and permit procedures
578
15.2.2.1 Introduction
578
15.2.2.2 Permits
578
15.2.2.3 Regulations, approvals and procedures
578
15.2.2.4 Compensations
579
15.2.3 Environmental impact assessment
580
15.2.3.1 Outline of the process
580
15.2.3.2 Enviromental impact studies
581
15.2.3.3 Existing environmental situation without the line project
581
15.2.3.4 Reference alternative
583
15.2.3.5 Environmental impacts of a new line
583
15.2.4 Route selection and line design in view of visual impact
583
15.2.4.1 Introduction
583
15.2.4.2 Conceptual approaches
584
15.2.4.3 Assessment through qualitative methods
584
15.2.4.4 Assessment through quantitative methods
584
15.2.4.5 Routing for minimum visual impact
585
15.2.4.6 Visualization of new lines
587
15.2.4.7 Design of components to reduce visual impact
588
15.2.5 Route selection in view of people
591
15.2.6 Route selection and line design in view of ecological systems
591
15.2.6.1 Introduction
591
15.2.6.2 Impacts on avifauna
591
15.2.6.3 Impacts on wild animals
592
15.2.6.4 Impacts on vegetation
593
15.2.6.5 Conservation and wilderness areas
593
15.2.7 Route selection in view of land use
593
15.2.7.1 Introduction
593
15.2.7.2 Agricultural areas
593
15.2.7.3 Forestry
594
15.2.7.4 Industrial areas and infrastructure developments
594
15.2.7.5 Urban areas
595
15.3 Survey on site
595
15.3.1 Steps of survey
595
15.3.2 Survey procedures and instruments adopted
596
15.3.2.1 Direct survey in the terrain
596
15.3.2.2 Indirect line survey
598
15.3.2.3 Terrain data banks
600
15.3.3 Survey of angle points and line alignment
600
15.3.4 Survey of terrain profile
601
15.3.5 Location of supports
601
15.3.6 Survey of existing lines
601
15.4 Line design and establishing of plans
603
15.4.1 Clearances
603
15.4.2 Determination of support locations, tower types and heights
605
15.4.2.1 Evaluation of the profile survey
605
15.4.2.2 Basis and relevant parameters
605
15.4.2.3 Manual tower spotting
606
15.4.2.4 Tower spotting and optimization by means of data processing . . . 607
15.4.3 Documentation of lines
610
15.5 Data processing for line design and administration
611
15.5.1 Data processing systems for planning of overhead lines
611
Contents
XXV
15.5.2 Establishing the longitudinal profile
15.5.3 Establishing the plan layout
15.5.4 Graphical Information System with integrated data bank
15.5.5 Administration of plans, lists and documents
15.6 References
611
614
616
617
617
16 Construction
16.0 Symbols
16.1 Construction planning
16.1.1 Introduction
16.1.2 Construction time schedule
16.1.3 Mobilisation and stockyard
16.2 Transportation
16.2.1 Means of transport
16.2.2 Access roads
16.2.3 Fences, gates and cattle-guards
16.3 Construction of foundations
16.3.1 Introduction
16.3.2 Concrete foundations black and slab foundations
16.3.3 Augerbored foundations
16.3.4 Driven pile foundations
16.3.4.1 Common rules
16.3.4.2 Steel piles
16.3.4.3 Steel piles grouted by mortar
16.3.4.4 Testing
\ j 16.3.5 Grillage foundations
16.3.6 Anchor foundations
16.3.7 Concrete for foundations
16.3.7.1 Ready-mixed and site-mixed concrete
16.3.7.2 Constituent materials
16.3.7.3 Requirements on concrete and concrete properties
16.3.7.4 Ready-mixed concrete
16.3.7.5 Site-mixed concrete
16.3.7.6 Handling and placing the concrete
16.3.7.7 Curing the concrete
; 16.3.7.8 Methods for verification of concrete properties
16.3.7.9 Quality supervision and quality management
jffB.4 Installation of earthing
18.5 Setting of tower stubs or bases
16.5.1 Methods and tools
|T 16.5.2 Inclination of angle and dead-end towers
|$6.6 Erection of supports
h 16.6.1 Introduction
?i 16.6.2 Assembly and erection by elevation
fi 16.6.3 Tower erection using a crane
. 16.6.4 Tower erection by means of a gin pole
SS. 16.6.4.1 Procedures
| i 16.6.4.2 Erection with a gin pole outside the tower
| t 16.6.4.3 Erection with gin pole in the tower centre
16.6.4.4 Erection with a gin pole in the tower at a leg member
& 16.6.5 Erection of guyed towers
16.6.5.1 Hoisting of a crossarm using a gin pole
621
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623
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XXVI
Contents
16.6.6 Tower erection using helicopters
16.6.6.1 Manual method
16.6.6.2 Use of an auxiliary mast
16.6.6.3 Erection by cranes
16.6.7 Bolts and torques
16.7 Installation of insulator sets and hardware
16.7.1 Insulator sets
16.7.2 Joints
16.8 Conductor stringing
16.8.1 General requirements
16.8.2 Stringing methods
16.8.3 Conductor stringing equipment
16.8.3.1 Requirements
16.8.3.2 Pulling ropes
16.8.3.3 Rope connections
16.8.3.4 Stringing blocks
16.8.3.5 Puller for conductor stringing
16.8.3.6 Tensioner
16.8.3.7 Reel stands
16.8.4 Conductor stringing
16.8.4.1 Preparations
16.8.4.2 Stringing procedure
16.8.4.3 Sagging the conductors
16.8.4.4 Terminating the conductors
16.8.4.5 Clipping-in of conductors
16.8.4.6 Installation of jumper loops
16.8.4.7 Installation of dampers and bundle spacers
16.8.4.8 Conductor replacement
16.8.4.9 Stringing conductors with optical
fibres
16.8.4.10 Installation of conductors adjacent to or crossing energized lines . .
16.8.5 Determination of initial sags
16.8.5.1 Requirements
16.8.5.2 Position of the conductor on stringing blocks and in clamps . . . .
16.8.5.3 Impact of conductor creep
16.8.5.4 Example: Sagging data for an overhead line in a mountainous area .
16.9 References
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650
650
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652
653
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653
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659
660
660
660
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664
664
664
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672
673
17 Commissioning, operation and line management
17.0 Symbols
17.1 Commissioning
17.1.1 Introduction
17.1.2 Supervision of approval, design and manufacturing stage
17.1.3 Supervision and acceptance of construction
17.1.4 Final inspection and acceptance
17.1.5 Quality assurance
17.1.6 Performance tests
17.1.6.1 Measurements of tower earthing resistance
17.1.6.2 Power losses and electrical resistance of conductors
17.1.6.3 Line energization test
17.1.6.4 Electrical and magnetic fields (EMF)
17.1.6.5 Vibration performance measurements
17.1.7 Energization and commence of operation
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677
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677
678
679
681
682
682
682
682
684
685
685
686
Contents
,17.2 Operation
17.2.1 Real-time monitoring of conductor ampacity
17.2.1.1 Targets and benefits
17.2.1.2 Direct methods
17.2.1.3 Indirect methods
17.2.1.4 Examples and experience
17.2.2 Thunderstorm monitoring and forecast
17.2.3 Ice observations
17.2.4 Galloping alerting system
17.2.5 Insulator contamination and performance
| JT.3 Asset management
17.3.1 Definitions
' 17.3.2 Introduction and targets
17.3.3 Risk management of line assets
17.3.4 Net present value of annual expenditures
17.3.5 Planned expenditures
17.3.6 Risk of failure
17.3.7 Consequences of a failure
17.3.8 Overhead line asset management process
-17.3.9 Data base
17.3.10 Management options
' 17.3.11 Example on management of risk of failure
17.3.11.1 Basic data
17.3.11.2 Calculation of planned expenditures and risks
17.3.11.3 Management options and assessment
?.4 Maintenance
'17.4.1 Introduction
£'17.4.2 Inspection
17.4.2.1 Reasons and procedures for inspections
17.4.2.2 Inspection classification and frequency
17.4.2.3 Foundations and stubs
17.4.2.4 Supports including corrosion protection
17.4.2.5 Conductors
17.4.2.6 Joints and
fittings
17.4.2.7 Insulators
17.4.2.8 Clearances
f
17.4.3 Corrective maintenance
17.4.3.1 Strategy
17.4.3.2 Refurbishment and upgrading of foundations
17.4.3.3 Renewal of coating, replacement of tower components
17.4.3.4 Repair of conductors
17.4.3.5 Replacement of insulators, fittings, dampers and spacers
17.4.3.5.1 Tasks and priorities
17.4.3.5.2 Dead-line work
17.4.3.5.3 Live-line work
17.4.3.6 Clearing of right-of-way, trimming of trees
17.4.3.7 Access roads
17.4.3.8 Earthing
117.4.4 Investigation of line failures
17.4.4.1 General
17.4.4.2 Causes of failure
17.4.4.3 Investigation procedures
XXVII
686
686
686
687
688
688
689
690
691
691
693
693
694
694
695
695
696
696
697
698
699
700
700
700
701
702
702
703
703
704
706
707
708
711
712
713
714
714
714
714
715
715
715
716
716
717
719
719
719
719
719
720
XXVIII
Contents
17.4.4.4 Experience on line failures
17.5 Reliability and availability
17.5.1 Introduction and definitions
17.5.2 Energy availability, general description and guidelines
17.5.2.1 Availability
17.5.2.2 Determination of energy availability, example
17.6 Line refurbishment, upgrading and uprating
17.6.1 Definitions
17.6.2 Uprating
17.6.2.1 Current uprating
17.6.2.2 Uprating by reconductoring or voltage increase
17.6.2.3 Replacement of earth wire by optical cables (OPGW)
17.6.3 Upgrading
17.6.3.1 Introduction
17.6.3.2 Upgrading of a 380/220 kV river crossing in Germany
17.6.3.3 Upgrading of a 380/110 kV line in view of increased ice loads
17.7 References
Index
721
723
723
725
725
726
727
727
728
728
728
729
729
729
729
. . . 730
731
735