1. HV XLPE CABLES
STATE OF THE ART
DESIGN / MANUFACTURE ISSUES
Nigel Hampton,
Application Manager - Power Cables
Borealis AB, Sweden.

2. ICC Fall 2003 Education Session
Content
n State of the art
Stress / thickness
Service performance
Downsizing
n Design
Temperature
Strength
Length
Ageing
n Manufacture
Degassing
Scorch

3. ICC Fall 2003 Education Session
Content
n State Of The Art
Stress / Thickness
Service Performance
Downsizing
n Design
Temperature
Strength
Length
Ageing
n Manufacture
Moisture
Degassing
Scorch
Purity

4. ICC Fall 2003 Education Session
Thicknesses of Insulation for HV Cables
0
5
10
15
20
25
25 50 75 100 125 150 175
Cable Voltage (kV)
Averagewallthickness
(mm)

5. ICC Fall 2003 Education Session
Electrical Stresses
0
2
4
6
8
0 2 4 6 8 10 12 14 16
Conductor stress (kV/mm)
CoreStress(kV/mm)
HV
EHV
Mean & 90% Conf Limits
MV

6. ICC Fall 2003 Education Session
Selected HV Experience
0
500
1000
1500
2000
25 50 75 100 125 150 175
VOLTAGE (kV)
CONDUCTORSIZE(SQMM)
Size Of Bubble Represents Length Of Installed Cores

7. ICC Fall 2003 Education Session
Thicknesses of Transmission Cables
0
5
10
15
20
25
1965 1970 1975 1980 1985 1990 1995 2000 2005
Thickness(mm)
66 110 132 138 154

8. ICC Fall 2003 Education Session
Use of EHV Technology to Down Size
0,7
0,8
0,9
1
1,1
10 12 14 16 18 20 22
Wall Thickness (mm)
RelativeValue
MATERIAL COST
WEIGHT
HV TECHNOLOGY
6 / 3 kV/mm
EHV TECHNOLOGY
9 / 6 kV/mm
1000SQMM, Pb SHEATH

9. ICC Fall 2003 Education Session
High Stress Gives Smaller Cables
>15% reduction in weight
5 - 10% reduction in material cost

10. ICC Fall 2003 Education Session
8
7
6
5
4
3
2
1
0
12
Wall thickness
Average stress
Volume
Requirement
14 16 18 20 22
Size Affects Electrical Requirement
Reference case - 2000mm2 150kVReference case - 2000mm2 150kV

11. ICC Fall 2003 Education Session
Content
n State of the Art
Stress / Thickness
Service Performance
Downsizing
n Design
Temperature
Strength
Length
Ageing
n Manufacture
Moisture
Degassing
Scorch
Purity

12. ICC Fall 2003 Education Session
Breakdown Stress - Design Stress

13. ICC Fall 2003 Education Session
Breakdown Stress - Design Stress
the winner of the 100m
should complete the
marathon in 1 hour 10 mins

14. ICC Fall 2003 Education Session
Designing Cables
n Design Life
n Size
n Temperature
n Safety
safetytempsizeage
breakdown
design
FFFF
E
E =

15. ICC Fall 2003 Education Session
What Is The Outcome?
safetysizeage
temp@breakdown
design
FFF
E
E =

16. ICC Fall 2003 Education Session
What Is The Outcome?
safetysizeage
temp@breakdown
design
FFF
E
E =
40
2,22,2 - 3,8 1,1

17. ICC Fall 2003 Education Session
What Is The Outcome?
safetysizeage
temp@breakdown
design
FFF
E
E =
mmThicknessmmkVEdesign 16
5.5
3/150/5.5
1.1*2.2*3
40
====
40
2,22,2 - 3,8 1,1

18. ICC Fall 2003 Education Session
Endurance Tests
0
0,3
0,6
0,9
0,1 1 10 100 1000 10000 100000
Time to failure (hours)
Probabilityoffailure
50kV/mm
33kV/mm
model
transmission
cables

19. ICC Fall 2003 Education Session
115kV cables taken from service after 20 Years
UN USED
USED
Slices Of Insulation
Taken From Cables

20. ICC Fall 2003 Education Session
Endurance Curve - Transmission Cables
0
5
10
15
20
25
30
35
40 1,E+00
1,E+01
1,E+02
1,E+03
1,E+04
1,E+05
1,E+06
Time (Hours)
Meanelectricalstress(kV/mm)
FAIL ON TEST
NO FAIL ON TEST
NO FAIL IN SERVICE
LONG TERM TESTSLONG TERM TESTS
TYPE
TESTS
TYPE
TESTS

21. ICC Fall 2003 Education Session
5mm
25mm
Size

22. ICC Fall 2003 Education Session
0
10
20
30
40
50
60
70
10 100 1000 10000
Length (m)
ElectricStrength(kV/mm)
Size
5mm
25mm

23. ICC Fall 2003 Education Session
Content
n State Of The Art
Stress / Thickness
Service Performance
Downsizing
n Design
Temperature
Strength
Length
Ageing
n Manufacture
Moisture
Degassing
Scorch
Purity

24. ICC Fall 2003 Education Session
Water / Moisture Remains A Concern
n Moisture Has A
Dramatic Effect On
Ageing
n Water Barrier Has
To Be Effective And
Protected
n Oversheaths &
Jackets Are
Important Parts Of
The Cable Design
0
10
20
30
40
50
60
1,E-02
1,E-01
1,E+00
1,E+01
1,E+02
1,E+03
1,E+04
1,E+05
1,E+06
TIME (HOURS)
MeanElectricalStress
(kV/mm)
VIRGIN RAMP BREAKDOWN
RAMP BREAKDOWN AFTER DRY AGEING
RAMP BREAKDOWN AFTER WET AGEING

25. ICC Fall 2003 Education Session
Dielectric Loss Measurements - HV Cable Models
0
10
20
30
0 20 40 60 80 100
Measuring Voltage (kV)
TangentDelta(10E-4)
DEGAS 130C DEGAS 22C
AS MADE 130C AS MADE 22C
Industry Standard HV Insulation

26. ICC Fall 2003 Education Session
110kV Foil Laminate Sheathed Cable
0
1
2
3
4
5
6
0 20 40 60 80 100 120 140 160 180 200
Aus gas ungs konzentration des Methan in der Is olierung in ppm
Ueberdruckinbar
Overpressure at 90°C
Overpressure at 23°C
methane concentration in insulation in ppm
Overpressureinbar

27. ICC Fall 2003 Education Session
Time taken for Degassing
0
5
10
15
20
25
30
5 10 15 20 25
Wall thickness (mm)
Degassingtime(days)

28. ICC Fall 2003 Education Session
0
0,5
1
1,5
2
2,5
as made max permitted long degassing GOAL FOR
TOMORROW
WeightLoss(%)
Degassing Data - TGA Method HD632

29. ICC Fall 2003 Education Session
Cable Inspection, Hot Oil Test
Lump found in inner semiconductive layer
Width: 0.5 mm
Height: 0.05-0.1 mm

30. ICC Fall 2003 Education Session
“The Carrot Scorch Test”
Typical “Carrot”
Die
Scorch [vol-%]
Temperature [°C]
0
125 130 135 140
20
40
60
80
∆SC=45%
∆T=8°C
- Effect of Temperature -
Level and Sensitivity Effected

31. ICC Fall 2003 Education Session
By product concentration [WT%]
Time to critical scorch evolution [mins]
IncreasingRunLength
Optimal Parameters For High Productivity
Decreasing Degassing Requirement
Today
Tomorrow

32. ICC Fall 2003 Education Session
CLEANLINESS - TAPE TEST
SIZE
RANGE
(MICRONS)
HV
TECHNOLOGY
MV
TECHNOLOGY
50 – 70 - -
70 –100 10 -
100 – 200 0 3
NUMBER AND SIZE IS
NOT EVERYTHING!
HOW DO WE ALLOW FOR
DIFFERENT:
MATERIALS
SHAPES
0
2
4
6
8
1 10 100
PERMITTIVITY
STRESSENHANCEMENT
FACTOR
R/a=1
R/a=0,1
WE NEED A
SMARTER SET OF
CRITERIA!!

33. ICC Fall 2003 Education Session
Electrical Stresses
0
2
4
6
8
0 5 10 15 20 25 30 35
Conductor stress (kV/mm)
CoreStress(kV/mm)

34. ICC Fall 2003 Education Session
Conclusions
n XLPE HV Cables have come a long way and have some exciting challenges ahead
n Much of the technology is well established and known
n Challenges for the future
use of proven EHV technology to downsize
long lengths
increased need
ATTENTION TO DETAIL → RELIABILITY