Prysmian-HV-Cables-2007.pdf

HighVoltageCables

High Voltage Cables

The history of cables

With long experience since 1912 Prysmian Cablesand Systems Oy is today one of the leading cablemanufacturers in the world.

Today

The Prysmian Group has more than 50 productionplants in several countries on all continents.In addition to this the company has a worldwidenetwork of sales and representative offices.

Prysmian Cables and Systems Oy, located in Pikkala,Finland, produces energy cables - from extra high(400 kV ) to low voltage, for land, submarine andoverhead applications - along with a wide range ofaccessories. All our products can be tailored tomeet the customer’s requirements.

Our company has been the forerunner in high voltagecable technology for several decades. We haveexperience in supplying all types of high voltagecable systems throughout the world with full turnkey capability.

2

High Voltage Cables

3

Environmental andreliability aspects

When planning a new supply route, considerationof the environment is becoming more and moreimportant due to regulation and public opinion.

The XLPE cables are environmentally friendlyand safe.

The cable system is invisible. The required right ofway is very small and normally after the installationthe land can be used again for its original purpose.This can result in considerable savings.

Reducing the electrical and magneticfields is also becoming moreimportant. The cable systemcan be designed accordingto different magnetic fieldrequirements, and theexternal electrical fieldsare zero.

Cable systems offerbetter safety to bothworkers and general pub-lic, with fewer dangeroussituations due to accidentalcontacts or flashovers.

Reliability of the network is an importantfactor because the loss of supply has high costconsequences. Cable systems are less vulnerablefor failures compared to overhead lines.

Prysmian sets High Standards

Partial discharges in the cable's insulation areregarded as one of the main reasons for electricalbreakdown. Most recognized national and inter-national standards permit discharges of 5 pC.However, our policy is not to allow deliveries ofcables with any detectable discharges. Our newtest set-up allows testing of up to 400kV cablesat a measuring sensitivity which is considerablybetter than the above requirement.

We are certified according to ISO 9001 Qualityand ISO 14001 Environmental Management Systemstandards for our activities.

High Voltage Cables

Completely Dry Curingand Cooling

With Prysmian's Completely Dry Curing and Coolingmethod (developed under the name of Nokia Cables)the insulation is kept absolutely dry during thewhole manufacturing process. This prevents theelectrochemical treeing during the whole lifetimeof the cable. Our high voltage cables are equippedwith a metallic moisture barrier protecting theinsulation from subsoil humidity.

With the CDCC method, Prysmian has strengthenedits position as one of the world's most prominentcable manufacturers and as a forerunner in the fieldof XLPE cables since 1975.

The conductor screen, insulation and insulation screenare extruded at the same time, i.e. triple extruded.

Curing takes place in a vulcanizing tube pressurizedby nitrogen gas. Besides fully dry curing, cooling indry conditions is another important feature.It is achieved by using nitrogen gas.

The insulation does notcome into contact withwater in any form duringthe whole manufacturingprocess. It is a well-knownfact that high voltageinsulation should be keptmoisture-free and researchshows that this also appliesto XLPE insulation.Prysmian's CDCC cablesrepresent high quality andhigh cable life expectancy.

4

Cross-linkedpolyethyleneinsulation manu-factured usingthe CDCCprocess.

Cross-linkedpolyethyleneinsulation manu-factured usingconventionalprocess.

Vertical CDCC-lineup to 420 kV

Conductor preheating

Clean room. Gravity feedingof insulation

On-line material purity control

Triple extrusion

Process control Autocure 3

X-ray wall thicknessmeasurement

Post heater

On-line relaxation

1

2

3

4

5

6

7

8

1

23

45

6

7

8

High Voltage Cables

On-line relaxation

First in the world, since 1994, our production linehas been equipped with the unique on-line relaxationsystem, giving benefits as:• increased impulse voltage withstand• reduced internal mechanical stresses• minimized shrinkback behaviour

The on-line relaxation unit consists of an additionalheating zone located in the middle of the coolingsection of the vulcanizing line. Insulation surfaceis heated up and cooled down again. This treatmentreduces significantly both internal mechanicalstresses and shrinkback of XLPE insulation.

Integrated optical fiber unit

Optical fibers in power cables can be used formeasuring the actual temperature along the cableline or for data transmission. Fiber units are normallyembedded under the lead sheath or between thescreen wires.

Temperature monitoring provides continuousmonitoring of cable temperatures, detecting hotspots, delivering operational status, conditionassessment and power circuit rating data.It is immune to electromagnetic interference andprovides reliable temperature measurements, idealfor use in high voltage cables.

Cables with optical fibers are denoted with letter´F´, for example HXCHBMK-2F.

5

Two samples from the same cable and the same test run.The only difference between these samples is the use of relaxation.

Non-relaxed Relaxed

Standard Specifications

We manufacture High Voltage Cables accordingto any international or national standard.The two most common standard constructionsare described on page 6-7.

High Voltage Cables

6

HXCHBMK / AHXCHBMK

Single core XLPE insulated powercable with copper wire screen andfoil laminate sheath

ConductorLongitudinally watertight segmental strandedand compacted copper or aluminium

Binder tapesSemiconducting waterblocking tapes and bindertapes

Conductor screenExtruded semiconducting copolymer compound

InsulationExtruded superclean XLPE compound

Insulation screenExtruded semiconducting copolymer compound

BeddingSemiconducting waterblocking tapes

Metallic screenA layer of copper wire helix and a coppercontact tape counter helix

Separation tapeSemiconducting waterblocking tapes andbinder tapes

Radial water barrierAluminium or copper foil laminate

Outer sheathExtruded PE or HFFR

1

2

3

4

5

6

7

8

9

10

1

2

3

4

5

6

7

8

9

10

High Voltage Cables

7

1

2

3

4

5

6

7

8

1

2

3

4

5

6

7

8

HXLMK / AHXLMK

Single core XLPE insulatedpower cable with lead sheath

ConductorLongitudinally watertight segmental strandedand compacted copper or aluminium

Binder tapesSemiconducting waterblocking tapes and bindertapes

Conductor screenExtruded semiconducting copolymer compound

InsulationExtruded superclean XLPE compound

Insulation screenExtruded semiconducting copolymer compound

BeddingSemiconducting waterblocking tapes

Metallic sheathExtruded lead, alloy E

Outer sheathExtruded PE, PVC or HFFR

Rated voltagesUo/U = 38/66 kVUm = 72.5 kVUp = 325 kVRated temperatures• Maximum permissible temp. of

conductor in continuous use 90°C• Maximum permissible temp. of

conductor in short-circuit 250°C( for durations up to 5 sec. )

Standard IEC 60840

Maximum permissible short-circuit currents for short-circuit duration of one second

Aluminium conductor

Copper conductor

Continuous current-carrying capacities

Cableslaid

Ingroundof 15°C

In airof 25°C

Ingroundof 15°C

In airof 25°C

Conductortemperature

65°C

90°C

90°C

65°C

90°C

90°C

Screencircuit

OpenClosedOpenClosedOpenClosedOpenClosedOpenClosedOpenClosedOpenClosedOpenClosedOpenClosedOpenClosedOpenClosedOpenClosed

Aluminium

Copper

Layingformation

Flat

Trefoil

Flat

Trefoil

Flat

Trefoil

Flat

Trefoil

Flat

Trefoil

Flat

Trefoil

Conductor

Electrical properties at 66 kV and 50 Hz

Maximum DC-resistance

Effective-resistance,screensbonded atboth ends



Flatformation

Trefoilformation

Flatformation

Trefoilformation

Flat formationTrefoil formation

at 20°C20°C65°C90°C20°C65°C90°C

at 20°C20°C65°C90°C20°C65°C90°C

DC-resistance of metallic screen at 20°C approx.

InductanceOperating capacitanceCharging current

Aluminiumconductor

Copperconductor





Constructional data

Outer diameter

Net weightwith Pb sheath

Recommended minimum bending radius during laying

With aluminium conductorWith copper conductorWith aluminium conductorWith copper conductor

Nominal cross-sectional area of conductor

kAkA

AAAAAAAAAAAAAAAAAAAAAAAA

Ω/kmΩ/kmΩ/kmΩ/kmΩ/kmΩ/kmΩ/kmΩ/kmΩ/kmΩ/kmΩ/kmΩ/kmΩ/kmΩ/kmΩ/km

mH/kmmH/kmµF/kmA/km

mmmm

kg/kmkg/km

m

mm2

75.6114.2

750640700680890770830805

1265110510951085

940740860820

1115900

1025980

1585130513551340

0.03670.0650.0680.0700.0470.0520.055

0.02210.0510.0520.0520.0330.0360.038

0.510.530.340.30

3.5

7474

1100016000

1.3

800

113.4171.4

910710830790

1080860990945

15551270133513201200

8201095100514151005130512052040150517651685

0.02470.0590.0590.0600.0370.0400.042

0.01510.0470.0460.0450.0240.0250.026

0.400.510.330.35

4.3

8385

1400022000

1.5

1200

47.271.4

575525545535680625645635930865820810730635685670865765815795

1185106510351025

0.06050.0840.0920.0970.0680.0780.084

0.03660.0610.0640.0660.0450.0500.0540.620.560.370.25

2.7

6767

840012000

1.2

500

28.342.8

435415415410515490490485685660605600560520535525660620630620880830775770

0.10000.1200.1360.1450.1060.1230.133

0.06010.0800.0890.0930.0670.0760.082

0.740.590.400.20

2.3

6060

68008750

1.1

300

151.2228.5

1040750930870

1235920

1110104518151390153515151390

8551240110516451055148513352420162020651940

0.01860.0560.0550.0550.0330.0350.036

0.01130.0470.0450.0440.0220.0220.023

0.350.500.320.40

4.8

9093

1650027500

1.7

1600

72 kV Cables 36/66 kV

Single core, XLPE-insulated

high voltage power cables

Sample Constructions

High Voltage Cables

8

High Voltage Cables

9

Constructional data

Outer diameter










Flatformation

Trefoilformation

Flatformation

Trefoilformation


at 20°C20°C65°C90°C20°C65°C90°C

at 20°C20°C65°C90°C20°C65°C90°C



Aluminium

conductor

Copper

conductor






Cableslaid

Ingroundof 15°C

In airof 25°C

Ingroundof 15°C

In airof 25°C


65°C

90°C

90°C

65°C

90°C

90°C

Screencircuit


Aluminium

Copper

Layingformation

Flat

Trefoil

Flat

Trefoil

Flat

Trefoil

Flat

Trefoil

Flat

Trefoil

Flat

Trefoil

Conductor


800

8283

1300018500

1.5

0.03670.0700.0720.0740.0480.0530.056

0.02210.0560.0560.0570.0340.0370.038

0.420.550.360.25

4.6

750625700675885750830800

1235107510851070

935720860815

1110875

1025975

1555127013501330

75.6114.2

1200

9294

1650024500

1.7

0.02470.0640.0640.0640.0380.0410.043

0.01510.0520.0500.0500.0250.0270.028

0.340.530.350.30

5.6

905690830785

1075840990940

15201230132513001190

7901085

9851410970

129511901995145017451655

113.4171.4

300

6767

810010050

1.2

0.10000.1230.1390.1480.1070.1250.134

0.06010.0840.0920.0960.0680.0770.083

0.620.610.420.15

3.3

435410415410510490490485675645605600560510530520660610630620870815775770

28.342.8

Aluminium conductor

Copper conductor

mmmm

kg/kmkg/km

m

mm2




kAkA

1600

99102

1900030000

1.8

0.01860.0610.0600.0600.0340.0360.037

0.01130.0520.0490.0480.0230.0240.0240.300.520.330.30

6.2

1035730930860

1230895

1110103517751350152514901380

8251230108016401015147513102360156520401900

151.2228.5

500

7474

1010013500

1.3

0.06050.0880.0960.1010.0690.0790.085

0.03660.0650.0680.0700.0460.0510.0540.510.580.390.20

3.8

575515545530675615640630915850815805730625685665860750810790

1165103510351020

47.271.4




Rated voltagesUo/U = 64/110 kVUm = 123 kVUp = 550 kVRated temperatures• Maximum permissible temp. of


conductor in short-circuit 250°C(for durations up to 5 sec. )

Standard IEC 60840


Constructional data


Outer diameter









Flatformation

Trefoilformation

Flatformation

Trefoilformation


at 20°C20°C65°C90°C20°C65°C90°C

at 20°C20°C65°C90°C20°C65°C90°C



Aluminium

conductor

Copper

conductor






Cableslaid

Ingroundof 15°C

In airof 25°C

Ingroundof 15°C

In airof 25°C


65°C

90°C

90°C

65°C

90°C

90°C

Screencircuit


Aluminium

Copper

Layingformation

Flat

Trefoil

Flat

Trefoil

Flat

Trefoil

Flat

Trefoil

Flat

Trefoil

Flat

Trefoil

Conductor


9294

1650024500

1.7

1200

0.02470.0640.0640.0640.0390.0420.043

0.01510.0520.0510.0500.0250.0270.028

0.340.530.350.30

6.7

905685830780

1075840990935

15201230132513001190

7901085

9851410970

129011851990145017451650

113.4171.4

99102

1900030000

1.8

1600

0.01860.0610.0600.0600.0340.0360.037

0.01130.0520.0500.0480.0230.0240.0240.300.520.330.30

7.5

1030725925855

1230895

1110103517701345152014901375

8201230107516351015147013102360156520351895

151.2228.5

8283

1300018500

1.5

800

0.03670.0700.0730.0740.0480.0530.056

0.02210.0570.0570.0570.0350.0370.039

0.420.550.360.25

5.5

745620695670885750825800

1235107510851070

935720860810

1110875

1025975

1555126513501325

75.6114.2

7474

1010013500

1.3

500

0.06050.0890.0970.1010.0700.0800.085

0.03660.0650.0680.0700.0460.0520.055

0.510.580.390.20

4.6

570515540530675615640630915845815805725620685660860750810790

1165103510301020

47.271.4

Aluminium conductor

Copper conductor

mmmm

kg/kmkg/km

m

mm2




kAkA

105109

2200035500

1.9

2000

0.01490.0620.0600.0590.0320.0340.034

0.00900.0540.0510.0490.0220.0220.022

0.260.510.320.35

8.2

1135745

1000905

1355920

1200110019801415168016351530

8251330113018251030160013802655162022602075

189.1285.7






conductor in short-circuit 250°C( for durations up to 5 sec. )

Standard IEC 60840


High Voltage Cables

10

High Voltage Cables

11


Constructional data


Outer diameter

Net weightwith Cu screen


Nominal cross-sectional area of screen






Flatformation

Trefoilformation

Flatformation

Trefoilformation


at 20°C20°C65°C90°C20°C65°C90°C

at 20°C20°C65°C90°C20°C65°C90°C



Aluminiumconductor

Copperconductor






Cableslaid

Ingroundof 15°C

In airof 25°C

Ingroundof 15°C

In airof 25°C


65°C

90°C

90°C

65°C

90°C

90°C

Screencircuit


Aluminium

Copper

Layingformation

Flat

Trefoil

Flat

Trefoil

Flat

Trefoil

Flat

Trefoil

Flat

Trefoil

Flat

Trefoil

Conductor


120095

97100

960018000

2.0

0.02470.0840.0850.0860.0480.0490.051

0.01510.0720.0720.0720.0350.0350.036

0.200.550.360.246.8

905610815730

1075745975880

15151125132012251190

6801055

8851410830

126510751985129517251535

113.4171.4

160095

104107

1150022000

2.1

0.01860.0790.0790.0790.0430.0430.044

0.01130.0680.0680.0670.0310.0310.031

0.200.530.350.27

7.5

1035650910795

1235795

1095970

17651235151513851375

7151185

9601635

880143011752340141020051735

151.2228.5

80095

8889

770013500

1.8

0.03670.0950.0980.1010.0580.0620.065

0.02210.0810.0820.0830.0450.0460.0470.200.570.380.20

5.6

750550690630885665820760

1235980

10851025

935610845745

1115750

1010900

1550112013451240

75.6114.2

50095

8080

61509300

1.6

0.06050.1180.1260.1310.0810.0900.095

0.03660.0940.0970.0990.0570.0610.0640.200.600.410.17

4.7

575465540510680560640605915790820790725535670620855650800740

1145925

1020965

47.271.4

200095

110114

1300026500

2.3

0.01490.0790.0790.0790.0430.0430.044

0.00900.0660.0650.0650.0290.0290.029

0.200.520.330.29

8.2

1135675985845

1360830

1185103519801325167515101530

740129010201825

915155512502640149522251890

189.1285.7






conductor in short-circuit 250°C(for durations up to 5 sec.)

Standard IEC 60840


mm2

mm2




kAkA

mmmm

kg/kmkg/km

m

Aluminium conductor

Copper conductor

High Voltage Cables

12


Constructional data


Outer diameter









Flatformation

Trefoilformation

Flatformation

Trefoilformation


at 20°C20°C65°C90°C20°C65°C90°C

at 20°C20°C65°C90°C20°C65°C90°C



Aluminiumconductor

Copperconductor






Cableslaid

Ingroundof 15°C

In airof 25°C

Ingroundof 15°C

In airof 25°C


65°C

90°C

90°C

65°C

90°C

90°C

Screencircuit


Aluminium

Copper

Layingformation

Flat

Trefoil

Flat

Trefoil

Flat

Trefoil

Flat

Trefoil

Flat

Trefoil

Flat

Trefoil

Conductor


120095

106108

1100019000

2.2

0.02470.0850.0860.0870.0490.0500.052

0.01510.0730.0730.0730.0350.0360.036

0.200.560.380.21

8.3

890600800715

1060735960865

14501085128511951170

6701030

8651390

825123510551895125016701495

113.4171.4

160095

113115

1300023500

2.3

0.01860.0800.0800.0800.0430.0440.045

0.01130.0690.0680.0680.0320.0310.031

0.200.540.360.23

9.2

1015640895780

1215785

1080950

16901190147513501350

7051160

9451610

870140011602235135519401690

151.2228.5

80095

98100

900015000

2.0

0.03670.0970.1000.1020.0600.0630.066

0.02210.0790.0800.0810.0420.0430.0450.200.580.400.18

7.3

730540670615865655800740

1160935

1040985955620865760

1135755

1035920

1520110513551250

75.6114.2

50095

9191

750011000

1.8

0.06050.1200.1270.1320.0830.0910.096

0.03660.0960.0990.1010.0590.0620.065

0.200.620.440.145.8

565460525500665555625595875760795770715535660610850645790730

1115905

1005955

47.271.4

200095

119122

1450028000

2.4

0.01490.0770.0760.0760.0400.0400.041

0.00900.0670.0660.0650.0300.0290.029

0.200.530.350.2510.0

1115665965830

1340820

1170101518901270162514701500

730125510001795

905152512302510143021501835

189.1285.7

245 kV Cables 127/ 220 kV



Aluminium conductor

Copper conductor

mm2

mm2




kAkA

mmmm

kg/kmkg/km

m




Standard IEC 62067


High Voltage Cables

13


Constructional data


Outer diameter









Flatformation

Trefoilformation

Flatformation

Trefoilformation


at 20°C20°C65°C90°C20°C65°C90°C

at 20°C20°C65°C90°C20°C65°C90°C



Aluminiumconductor

Copperconductor






Cableslaid

Ingroundof 15°C

In airof 25°C

Ingroundof 15°C

In airof 25°C


65°C

90°C

90°C

65°C

90°C

90°C

Screencircuit


Aluminium

Copper

Layingformation

Flat

Trefoil

Flat

Trefoil

Flat

Trefoil

Flat

Trefoil

Flat

Trefoil

Flat

Trefoil

Conductor


120095

115117

1250020500

2.3

0.02470.0890.0890.0900.0510.0520.053

0.01510.0760.0750.0750.0370.0370.037

0.200.580.390.1811.6

870595785700

1045730945855

14201080126511801140665

1005850

1370820

121510451855125016451480

113.4171.4

160095

122124

1450025000

2.5

0.01860.0830.0820.0830.0460.0450.046

0.01130.0720.0700.0700.0340.0320.033

0.200.560.380.2012.7

995630875765

1195780

1065940

16501185145513351320

6951130

9251585

865137511452185136019101675

151.2228.5

80095

112112

1150016500

2.2

0.03670.1000.1020.1050.0620.0650.068

0.02210.0830.0830.0840.0440.0450.0460.200.610.420.16

9.9

715535660605855655790735

1125925

1020975935610845745

1120750

1020905

1480110013351235

75.6114.2

63095

111111

1100015000

2.2

0.04690.1100.1140.1180.0720.0770.081

0.02830.0910.0920.0930.0530.0550.057

0.200.640.450.13

8.2

635500590550760605705665990845905870805570735665960695880805

1250995

11351070

59.590.0

200095

128131

1600029500

2.6

0.01490.0800.0790.0790.0420.0420.042

0.00900.0700.0680.0680.0320.0300.030

0.210.550.360.2213.9

1090655945815

1320815

1155100518451265160514601460720

1225975

1765895

149512152455143521201825

189.1285.7




Aluminium conductor

Copper conductor

mm2

mm2




kAkA

mmmm

kg/kmkg/km

m




Standard IEC 62067


High Voltage Cables

14






Flatformation

Trefoilformation

Flatformation

Trefoilformation


at 20°C20°C65°C90°C20°C65°C90°C

at 20°C20°C65°C90°C20°C65°C90°C



Aluminiumconductor

Copperconductor






Cableslaid

Ingroundof 15°C

In airof 25°C

Ingroundof 15°C

In airof 25°C


65°C

90°C

90°C

65°C

90°C

90°C

Screencircuit


Aluminium

Copper

Layingformation

Flat

Trefoil

Flat

Trefoil

Flat

Trefoil

Flat

Trefoil

Flat

Trefoil

Flat

Trefoil

Conductor






Constructional data


Outer diameter




Aluminium conductor

Copper conductor




Standard IEC 62067





kAkA

mm2

mm2

mmmm

kg/kmkg/km

m

0.03670.1010.1030.1060.0630.0660.069

0.02210.0840.0840.0840.0450.0460.0470.200.620.440.1410.3

715540660605855655790735

1125935

1025980930615840740

1110755

1010905

1450110013201230

75.6114.2

80095

123122

1300018500

2.4

0.02910.0940.0950.0960.0560.0570.059

0.01760.0790.0780.0790.0400.0400.0410.200.600.420.1611.5

800570725660960700875805

12651015115010901045

645930805

1255795

1130985

1670119515001375

94.5142.8

100095

124123

1350020500

2.5

0.02470.0900.0900.0910.0520.0520.054

0.01510.0770.0760.0760.0380.0380.038

0.200.590.410.1712.3

865595775700

1040730940855

13901080125011751130

660995840

1360820

121010351825125016301470

113.4171.4

120095

124125

1400022000

2.5

0.01860.0850.0830.0840.0470.0460.047

0.01130.0740.0710.0710.0350.0330.033

0.210.570.380.1914.0

980625865760

1185775

1055935

16301185144013301300

6901115

9101570

860136511352160135518951665

151.2228.5

160095

127128

1550026000

2.6

High Voltage Cables

15

Different kinds of power cable constructions arerequired to transport electrical energy fromthe power station to the consumer.The following factors are important when selectinga suitable cable construction:• Maximum operating voltage• Insulation level• Frequency• Load to be carried• Daily load curve• Magnitude and duration of possible overloads

currents phase-to-phase and phase-to-earth• Connection between overhead and cable line

(whether directly or via a transformator)• Insulation level of equipment

(bareconductor insulators, arresters, etc.)• Voltage drop• Length of line• Profile of line

• Mode of installation:- underground (whether directly or in ducts) - in air ( if in a tunnel, the dimensions andmode of ventilation of the tunnel )

• Chemical and physical properties of the soil:- whether rocky, sandy, clay or boggy;moist or dry- chemical agents liable to cause corrosion etc.- the maximum thermal resistivity of the soil

• Maximum and minimum ambient air andsoil temperatures, bearing in mind nearbyhotwater pipes and other factors liable toheat the cables

• Specifications and requirements to be met• The cable should be economical to use;

an optimum cross-sectional area can becalculated based on the capital costs ofthe cable and its running costs incurred bythe power losses in the cable

Selectinga powercable

The electrical properties and continuous currentratings apply for lead sheathed cables with ournormal sheath thickness. The thickness of sheathand especially the cross-section of copper screencan be adjusted according to the required shortcircuit rating of sheath or screen.

Where loading is cyclic, appreciable increase incurrent capacities may be justified. Refer to IECPublication 60853 for calculation of the cyclicratings.

In cable circuits having no magnetic saturatingmaterials the positive and negative sequenceimpedances are equal and can be deduced from

the tabulated effective resistance and inductancevalues corrected as required for frequencies otherthan 50Hz.

Zero sequence impedance for solidly bondedsystems can be roughly estimated as the sumof the resistances of conductor and sheath anda reactance of 0.05 to 0.1 ohms /km dependingon the proportion of diameters of sheath andconductor at 50 to 60 Hz. For single point bondedsystems the zero sequence impedance dependson the ground wires and any other groundedmetallic objects along the cable route.

Usingthe tables

High Voltage Cables

16

Voltages Rated voltage

The voltage which forms the basis for certainoperating characteristics and test conditions iscalled the rated voltage and is denotedUo /U whereUo = the voltage between the conductor and

earth or earthed metallic cover(concentric conductor, screen,armouring, metal sheath)

U = the voltage between the phase conductors

Operating voltage

Um = the maximum continuously permissibleoperating voltage of the network at any time

or in any part of the network, excludingtemporary fluctuations such as those occuringduring switching or faults.

Relationship between Uo/U and Um in threephase systems are as follows according toIEC specifications:

Uo/U kV 36/66 64/110 76/132 127/220 190/345 220/400

Um kV 72.5 123 145 245 362 420

Uo/U kV 40/69 66/115 80/138 132/230 200/345

Um kV 72.5 121 145 242 362

CompleteSystemSupply

It is essential that the accessories and cables aretype-tested together forming a complete system.We supply a full range of accessories and fittingsfor the splicing and terminating as well as tools

and equipment, complete with instructions forinstallation. We also provide planning andsupervision of the complete system packages.

Power cables ranging from 72.5 kV to 420 kVcan be manufactured also according to otherstandards (eg. AEIC, VDE, BS, SEN ), regulationsor specifications in-line with the customers’requirements.

Customdesignedcables

Ac1973.5

mm2A =CircularMils

In American standards the cross section areais expressed in Circular Mils Ac.

Cross-Sections in mm2 converted into Circular Mils

Weights, dimensions and characteristic dataare approximate. Deviations due todifferent constructions are reserved.

Weightsanddimensions

Standards The cables described in this catalogue are ourstandard types, and their performance has beenproven in operation.

Construction and tests are in accordance with IECpublications where applicable.

and according to USA Standard C-84: 1-1995

mm2 185 300 500 800 1200 1600 2000

kcmil 365 590 990 1580 2370 3160 3950

High Voltage Cables

17

Our standard embossed or surface printed outersheath marking on round cables consists of:

• name of manufacturer• type designation, cross-sectional area of con-

ductor, rated voltage and year of manufacture

• continuous length marking every meter orevery few feet.

Example:AHXLMK 1x300 mm2 132 kV 2006 1234 m

Sheathmarking

Minimum permissible bending radii during laying:

• during pulling of power cables, the bending radii should not be smaller than the values given on pages 8-14• in the case of single bends, the above values

may be reduced to a min. of 70% if thecables are carefully and evenly bent onlyonce before a termination ( around a pre-fabricated bow, if necessary).

Max. permissible pulling tension during laying:

• during laying of power cables particularattention must be paid to the permissibletensile forces

• permissible tensile forces when pulling bycable pulling grip:F = A x 15 N/mm2

(cable with Al-conductor)F = A x 20 N/mm2

(cable with Cu-conductor)maximum value in both cases is 8500 N

• maximum recommended tensile forces whenpulling eye is attached to the conductor:

Al-conductors; ≤ 800 mm2, F = A x 70 N/mm2

> 800 mm2, F = A x 50 N/mm2

Cu-conductors; ≤ 800 mm2, F = A x 90 N/mm2

> 800 mm2, F = A x 70 N/mm2

A = cross-sectional area of conductor in mm2 (without screen and conc. conductor)

Minimum permissible cable temperature duringlaying:

• XLPE insulated cables U > 30 kV; -5°C for HFFR and PVC-sheath, -15°C for PE-sheath.At lower temperature the cables must be adequately warmed up beforehand.This can be done by storing the cables in a heated room for several days or by means of special equipment.

Layinginformation

Direct Current resistance

The maximum DC resistance values of conductorsat 20°C are shown in cable standards.The DC resistance at other conductor tempe-ratures may be calculated using the equation:

R=R20 [1+α20( t - 20°C)]R= DC resistance at temperature t, Ω/kmR20 = DC resistance of cond. at 20°C, Ω/kmt = temperature of conductor, °Cα20 = temperature coefficient of the resistance

at 20°C, 1/°C

for copper conductors α20 = 0.00393for Al. cond. and sheath α20 = 0.00403for lead alloy sheath α20 = 0.00400

On pages 8-14 are given:

• maximum DC resistance of conductors at20°C ( in accordance with IEC 60228)

• calculated DC resistance of metallic sheathsand metallic screens at 20°C

Effective resistance

The effective resistance (= alternating currentresistance) is made up of the DC resistance andthe extra resistance, which takes into accountadditional losses caused by the currentdisplacement in the conductor ( skin effect,proximity effect ), dielectrical losses in insulationcirculating currents in the metal sheath or screenand eddy currents as well as magnetic reversal inthe armour.On pages 8-14 are given effective resistanceof conductors at 20°C and at maximum conductortemperature. They are based on the followingpresumptions:

• frequency 50 Hz• closed screen circuit• distance between single core cables

- in case of flat formation = one cable diam.- in case of trefoil formation = cables touchingeach other.

Resistances

The values for the inductance of single core cableshave been calculated based on the followingpresumptions:

• open screen circuit

• distance between single core cables- in case of flat formation = one cable diam.- in case of trefoil formation = cables touchingeach other.

Inductance

Operatingcapacitance,

chargingcurrent andearth fault

current

The values for the operating capacitance of thecables are average values based on measurementsand calculations.The values for the charging current are valid ata temperature of 20°C, at a frequency of 50 Hzand at a rated voltage of the cable.

The values of capacitance, charging currentand earth fault current will not change whenusing XLPE insulated cables when the tempe-rature increases from 20°C to the maximumpermissible continuous conductor temperature.

High Voltage Cables

18

Continuouscurrent-carryingcapacity

A separate group of three single core cables canbe continuously loaded according to the tableson pages 8 to 14 if the presumptions below arefulfilled. Correction factors for other installationsare given in tables 1-7.The current-carrying capacities are calculated inaccordance with the IEC Publication 60287 andunder the presumptions given below.

Presumptions• One three-phase group of single core cables• Maximum permissible temperature of inner

conductor in continuous use:• XLPE insulated cables 90°C• Ambient air temperature 25°C• Ground temperature 15°C• Depth of laying of cables 1. 0 m• Distance between single core cables:

- in case of flat formation = one cable diam.- in case of trefoil formation = cables touchingeach other

• Thermal resistivity of soil 1. 0 K m/W• Cable in air = heat dissipation conditions

same as if cables in free air.• Open screen circuit in single core cable

group = circuit of metal sheaths, concentric conductors or metallic screens connected

to each other and earthed at one pointonly = screens bonded at a single point.In addition, screen circuit is considered open when cross-bonded at equal interval.

• Closed screen circuit in single core cable group = circuit of metal sheaths, concentric conductors or metallic screens connected to each other at both ends of the group and earthed at least at one end = screens bonded at both ends.

XLPE-insulated cables buried directly in groundXLPE-insulated cables can continuously be loadedto a conductor temperature of 90°C.In underground installations, if a cable in theground is continuously operated at this highestrated conductor temperature, the thermal resistivityof the soil surrounding the cable may in the courseof time increase from its original value as a resultof the drying-out processes. As a consequence,the conductor temperature may greatly exceedthe highest rated value.

Using single-point bonding or cross-bondinginstead of both-end bonding results in considerableincrease in current carrying capacity.

Short-circuitcurrentcapacity

The following tables of correction factors are tobe applied to the current-carrying capacity wheninstallation conditions vary from the presumptionsabove.

The rating for most conditions can be quicklyestimated by multiplying the continuous current-carrying capacity value by the correction factorsgiven in the appropriate tables 1-7.

Correctionfactors forthe current-carryingcapacity

Table 2.

Correction

factors for

different

thermal

resistivities

of soil

Table 1.

Correction

factors for

groups of

cables buried

directly

in ground

When planning cable installations, care has to betaken that the cables and fittings chosen arecapable of withstanding the expected dynamicand thermal short-circuit stresses.

The dynamic stresses depend on the max.asymmetric short-circuit current and the thermalstresses on the mean short-circuit current.

Dynamic stressesGenerally cables and their standard accessorieswill withstand the dynamic stresses under short-circuit conditions, but near the power stations itis important to take into consideration the dynamicshort-circuit current capacity and to pay attentionto the technique of installation.

Thermal stressesOn pages 8 to 14 are given the max. permissibleshort-circuit currents for short-circuit durationof one second and the values are based on thefollowing presumptions:• before short-circuit the temperature of

conductors = max. permissible temperature of conductor in continuous use

• max. permissible temperature of conductor in short-circuit is 250°C for XLPE-insulated cables

• the permissible short-circuit currents forshort-circuit duration of 0. 2 up to 5 seconds may be calculated by multiplying the value of max. permissible short-circuit current for short-circuit duration of one second by the figure1/ t, where t is the duration of short-circuitin seconds.

The values apply to groups of three single core cables ( in trefoil or flat formation)without or with spacing between the cable groups horizontally placed.

Examples of thermal resistivities of soil:

• dry sand (moisture content 0% ) 3.0 K m/W• dry gravel and clay 1.5 K m/W

• semi-dry gravel and sand (moisture content 10% ) 1.2 K m/W• semi-dry and moist gravel 1.0 K m/W• moist clay and sand ( moisture content 25%) 0.7 K m/W

Thermal resistivity of soil Km/W

Correction factor

0.7

1.10

1.0

1.00

1.2

0.92

1.5

0.85

2.0

0.75

2.5

0.69

3.0

0.63

Spacing betweengroups of cables, mm

0 (touching )70

250

20.790.850.87

30.690.750.79

40.630.680.75

50.580.640.72

60.550.600.69

80.500.560.66

100.460.530.64

Numbers of groups of single core cables beside each other

High Voltage Cables

19

Table 7.

Correction

factors for

different groups

of three single

core cables

laid in the air

This appliesonly whenthe cabletemperaturedoes notaffect theambient airtemperature.

Table 3.

Correction

factors for

different

installation

depths in ground

Table 4.

Correction

factors for

different ground

temperatures

Table 5.

Correction

factors for

different cables

in unfilled

plastic pipes

For parallel ducts with a group of three single core cables in each andwith the cables equally loaded the current-carrying capacity indicatedon pages 8 to 14 for cables buried directly in ground shall be reducedby correction factors given above.

The reduction in current carrying capacity can be avoided if the pipesafter cable pulling are filled with material thermally equalto the ambient ground.

If factors in table 5 are used, factors in table 1 are not applicable.

Spacing betweenthe tubes, mm

0 (touching)70

250

10.80

20.750.750.75

30.650.700.70

40.600.650.70

50.600.600.70

60.550.600.65

80.550.550.65

100.500.550.65

Numbers of tubes beside each other

Table 6.

Correction

factors for

different ambient

air temperatures

Depth of laying, m

Rating factor

0.50-0.70

1.05

0.71-0.90

1.02

0.91-1.10

1.00

1.11-1.30

0.97

1.31-1.50

0.95

Conductor temperature

C°90807065

-51.131.141.171.18

01.101.111.131.14

51.061.071.091.10

101.031.041.041.05

151.001.001.001.00

200.960.960.950.95

250.930.920.900.89

300.890.880.850.84

350.860.830.800.77

400.820.780.730.71

450.770.730.670.63

Ground temperature, C°

Conductor temperatureC°90807065

101.121.141.181.20

151.081.091.121.14

201.041.051.061.07

251.001.001.001.00

300.950.950.930.93

350.900.890.860.85

400.850.840.790.77

450.800.770.710.68

500.740.690.620.57

550.680.610.520.45

Ambient air temperature, C°

Type of layingCables laid in flat formationSpacing = One cable diameter (d).Distance from the wall not less than 20 mm.

Cables laid in trefoil formationSpacing = Two cable diameters (2d).Distance from the wall not less than 20 mm.

1

0.92

2

0.89

3

0.88

1

0.95

2

0.90

3

0.88

0.920.870.840.82

0.890.840.820.80

0.880.830.810.79

1236

1.000.970.960.94

0.970.940.930.91

0.960.930.920.90

1236

0.950.900.880.86

0.900.850.830.81

0.880.830.810.79

1.001.001.001.00

0.980.950.940.93

0.960.930.920.90

1

0.89

2

0.86

3

0.84

1

0.94

2

0.91

3

0.89

Number of groups 20 mm

dd

20 mm

dd

0.3 m

20 mm

dd

0.3 m

Correction factor Correction factorOn floor

Numberof trays

On metal trays(restricted aircirculation)

Numberof ladders

On metal ladders

20 mm2d

2d

0.3 m

20 mm2d

2d

0.3 m

20 mm2d

2d

0.3 m

20 mm4d

2d

Arrangements where reductionof current is not necessary

The cooling of cables in flat formationby increased spacing will get better whilethe losses in metallic screens and sheathswill increase reducing the current-carryingcapacity. Each case must be calculatedseparately.

Systems placed on topof each other

Correction factorCorrection factor

20 mm

d

d

2d

On structures or on wall

A. L

eppä

lä O

y 1

1/2

00

6

5.0

00

PRYSMIAN CABLES AND SYSTEMS OY

P.O.Box 13

FI-02401 Kirkkonummi, Finland

Phone +358 10 77551

Fax +358 9 682 1545

www.prysmian.fi

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