Power cable technology

436 Pages·2016·10.225 MB·English

by  Ganguli, Sushil Kumar, Kohli, Vivek

Power Cable
Technology
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Power Cable
Technology
Sushil Kumar Ganguli
Vivek Kohli
CRC Press
Taylor & Francis Group
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© 2016 by Taylor & Francis Group, LLC
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Version Date: 20160119
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Contents
Preface ......................................................................................................................xi
Authors ...................................................................................................................xv
1. Introduction .....................................................................................................1
2. Basic Materials for Manufacturing Various Types of Electric
Power Cables ....................................................................................................9
2.1 Conductor Material ...............................................................................9
2.1.1 Copper .....................................................................................10
2.1.2 Aluminium .............................................................................12
2.2 Insulating Materials ............................................................................14
2.2.1 Paper ........................................................................................15
2.2.2 Impregnation and Impregnating Oil ..................................16
2.2.3 Synthetic Polymers as Insulating Material ........................17
2.2.3.1 History of Development ........................................17
2.2.3.2 Polythene .................................................................17
2.2.3.3 Cross-Linked Polythene ........................................19
2.2.3.4 Peroxide Cure XLPE Compound .........................23
2.2.3.5 Moisture-Cured XLPE ...........................................23
2.2.3.6 Solar Power for Curing Sioplas ............................25
2.2.3.7 Recent Development on XLPE Compound.........26
2.2.3.8 Polyvinyl Chloride .................................................28
2.3 Fillers .....................................................................................................29
2.3.1 Carbon Black ...........................................................................30
2.3.2 Lubricants ...............................................................................30
2.3.3 Colourant.................................................................................30
2.4 Other Chemicals ..................................................................................30
2.4.1 PVC Compounding ...............................................................31
2.4.2 Reprocessing of PVC Compound ........................................32
2.4.3 Special Polymer Compounds ...............................................33
2.4.4 Metallic Screen or Sheath .....................................................34
2.4.4.1 Lead ..........................................................................34
2.4.4.2 Aluminium ..............................................................35
2.4.4.3 Armour Materials...................................................35
3. Wire Drawing: Copper and Aluminium .................................................37
3.1 Wire Drawing Process ........................................................................43
3.1.1 The Die ....................................................................................45
3.1.2 Constructional Features of a Drawing Ring ......................50
v
vi Contents
3.1.3 Lubricating Oil .......................................................................54
3.1.4 Selection of Wire Dimension ................................................58
3.1.5 Annealing ...............................................................................60
3.1.5.1 All Aluminium Alloy Wire...................................67
3.1.6 Storage and Transport ...........................................................70
3.1.7 Quality of Input Material and Drawn Wires .....................70
3.1.8 Further Consideration ...........................................................71
3.2 Wire Drawing Machine ......................................................................74
3.2.1 Segmental Wire to Make a Smooth Conductor .................77
3.2.2 Design Consideration ............................................................78
3.2.2.1 Calculation of Segmental Wire Shapes ...............78
3.2.3 Profiled Wire Drawing ..........................................................85
4. Conductor Formation–Stranding: Theory and Practice ........................87
4.1 Sector-Shaped Conductor for an 11,000 V cable ...........................112
4.2 Elliptical/Oval-Shaped Conductor for a 33,000 V Cable .............118
4.3 Manufacturing of Conductor with Profiled Wire ........................134
4.3.1 Stranding ...............................................................................134
4.3.2 Messenger Conductor for Aerial Bunch Cables ..............135
5. Insulation and Insulated Conductors.....................................................137
5.1 Insulation ...........................................................................................137
5.2 Application of Insulation on Conductors ......................................149
5.2.1 Paper Insulation ...................................................................149
5.2.2 Process of Impregnation .....................................................152
5.2.3 Synthetic Polymers as Insulating Materials .....................153
5.2.3.1 Their Production Technique and
Application ........................................................153
5.3 Pay-Off ................................................................................................165
5.3.1 Pre-heater ..............................................................................167
5.3.2 Cooling System .....................................................................167
5.3.3 Haul-Off System ...................................................................169
5.3.4 Take-Up Unit ........................................................................169
5.3.5 Thermosetting Cross-Linked Polymers ...........................169
5.4 Horizontal Continuous Vulcanisation System .............................176
5.4.1 Concept of Vulcanising Line ..............................................176
5.4.2 CCV Line ...............................................................................177
5.5 Degassing: For HV and EHV Cables ..............................................187
5.6 Sioplas System of Curing and Manufacturing XLPE Cables ......187
5.7 Irradiation System of Curing Polythene Insulation .....................189
5.8 Basic Concepts of Radiation Processing ........................................190
5.8.1 Absorbed Dose Definition ..................................................190
5.8.2 Temperature Rise versus Absorbed Dose ........................190
5.9 Processing Methods ..........................................................................192
Contents vii
6. Assembling and Laying Up of Multicore Cables and Protective
Metal Sheathing ..........................................................................................195
6.1 Taping .................................................................................................204
6.2 Protective Sheath for Laid-Up Cable Core (Mechanical
and Electrical Protection) .................................................................207
6.3 Metal Covering (Lead) ......................................................................207
6.4 Aluminium ........................................................................................213
6.5 Corrugated Steel Tape ......................................................................219
6.6 Calculation of Short-Circuit Rating Capacity for Metal Sheath ......220
6.7 Earth Bonding of HV and EHV Cable Sheath ..............................222
7. Armouring and Protective Covering ......................................................225
7.1 Armouring .........................................................................................225
7.1.1 Steel Tape Armouring .........................................................225
7.1.2 Galvanised Steel Wire or Flat Steel Strip Armouring ....228
7.2 Protective Covering ..........................................................................234
7.2.1 Extruded Thermoplastic (Inner and Outer Sheath) ........234
7.2.2 Grade of Material .................................................................237
8. Electrical Parameters for Cable Design .................................................241
8.1 Insulation and Insulating Materials ...............................................249
8.1.1 Thickness of Insulation: Consideration ............................254
8.2 Thermal Resistivity ...........................................................................272
8.2.1 Two Single-Core Cable Sheaths Bonded at Each End .....275
8.2.2 HV and EHV AC Systems ..................................................276
8.2.3 Three-Phase Circuit with Flat Formation.........................279
8.2.3.1 Sheath Bonded at One End .................................279
8.2.3.2 Sheath Bonded at Both Ends Together ..............280
8.2.4 Metallic Sheath or Screen Loss Factors .............................282
8.2.5 Single-Core Cable Sheath Bonding ...................................283
8.3 Voltage Induced in the Conductor of a Control Cable
When Laid alongside an Electrified Railway Track .....................291
8.4 Transmission of High-Frequency Signal through HV
and EHV Cables ................................................................................295
9. Quality Systems, Quality Control and Testing ....................................299
9.1 What Is Quality? ...............................................................................299
9.2 Testing of Cable .................................................................................301
9.2.1 Tests on Raw Materials .......................................................302
9.3 Tensile Strength .................................................................................303
9.4 Elongation ..........................................................................................303
9.5 Ageing Test .........................................................................................306
9.6 Hot Set Test (A Measure to Determine the Amount of
Cross-Linking Achieved) for Cured Materials such as XLPE
and Elastomers ..................................................................................308
viii Contents
9.7 Solvent Extraction .............................................................................309
9.7.1 Test Evolution .......................................................................309
9.7.1.1 Insulation Resistance Test ...................................311
9.7.1.2 Capacitance and Tan δ Test .................................313
9.8 Null Detector .....................................................................................314
9.9 Interface Suppression .......................................................................314
9.10 Protection ...........................................................................................314
9.11 Resistance of the Conductor ............................................................315
9.12 Measuring Low Resistance Using the Kelvin Double Bridge ....315
9.13 Wheatstone Bridge to Measure Conductor Resistance
on Completed Cables ........................................................................317
9.14 Wheatstone Bridge Theory ..............................................................317
9.15 AC Voltage Test ..................................................................................319
9.16 Partial Discharge Test .......................................................................320
9.17 Impulse Voltage Test .........................................................................326
9.17.1 Inductance .............................................................................327
9.18 Dimensional Check ...........................................................................328
9.19 Measurement of Armour Wires and Tapes ...................................330
9.20 Voltage Test for 4 h ............................................................................330
9.21 Type Tests, Electrical .........................................................................330
9.22 Cables with Conductor and Insulation Screens ...........................331
9.22.1 Special Provisions ................................................................331
9.23 Bending Test ......................................................................................331
9.24 Heating Cycle Test ............................................................................332
9.25 Resistivity of Semiconducting Screens ..........................................332
9.26 Test for Longitudinal Watertightness ............................................334
9.26.1 Water Absorption Test on Insulation ................................334
9.27 Flame Propagation Tests under Different Conditions .................336
9.28 LOCA Test for Nuclear Plants .........................................................337
9.28.1 LOCA Qualification .............................................................337
9.29 Test and Measurement Facilities .....................................................338
9.30 Synergism Simulator ........................................................................339
9.31 Cables for Offshore Wind Firms and Oil Exploration
Rigs: Hyperbaric Test ........................................................................339
9.32 Checking for Leakages in Each Test ...............................................341
10. Special Cables..............................................................................................343
10.1 Aerial Bunch Cables .........................................................................343
10.1.1 Raw Materials .......................................................................345
10.1.1.1 Conductor Material ..............................................345
10.1.1.2 Messenger Conductor Material ..........................347
10.1.1.3 Insulating Materials .............................................348
10.1.2 Polymeric Compounds ........................................................348
10.1.2.1 Polyvinyl Chloride ...............................................348
10.1.2.2 Polythene ...............................................................350
Contents ix
10.1.2.3 Cross-Linked Polythene ......................................352
10.1.2.4 Wet Curing Process (Sioplas-Grafted
Compound) ...........................................................353
10.1.2.5 Copper Tape for Screening .................................355
10.1.2.6 Constructional Features ......................................356
10.2 Direct Current Cables .......................................................................361
10.2.1 Insulation Material ..............................................................368
10.2.2 Volume Resistivity ...............................................................368
10.2.3 Space Charge Characteristics .............................................368
10.2.4 DC V–t Characteristics ........................................................369
10.2.5 Conclusion ............................................................................371
10.3 Umbilical Cables................................................................................372
11. Power Cable Laying, Jointing and Installation ....................................375
11.1 Backfilling of Trenches and in Pipes ..............................................385
11.2 Selected Materials Such as Sands as Backfill Material ................385
11.3 Ducts ...................................................................................................386
11.4 Cable Laying on Steel Trays and Racks (Both for LV
Distribution and for MV, HV and EHV Transmission Cables).....386
11.5 Joints and Terminations ...................................................................387
11.6 Desirable Design Features ...............................................................388
11.7 Jointing of Cable and Conductor ....................................................388
11.8 Crimping and Compression Joints .................................................391
11.9 Welding Methods ..............................................................................392
11.10 Insulating the Joint ...........................................................................393
11.11 Insulation: Low-Voltage Cable from 400/440 to 3000/3300 V
PVC Insulated ....................................................................................393
11.12 HV and EHV Joints ...........................................................................397
11.13 Stress Control .....................................................................................398
11.14 Straight Through Joint on EHV Cable ...........................................402
11.15 Termination ........................................................................................406
11.16 HV and EHV Cable Terminations ..................................................407
11.17 Thermomechanical Problems..........................................................407
11.18 Aerial Bunch Cables and Screen Terminations (11 and
33 kV Cables) ......................................................................................411
11.19 Tests Conducted after Installation ..................................................412
References ...........................................................................................................415
Index .....................................................................................................................417