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HV XLPE CABLESSTATE OF THE ART
DESIGN / MANUFACTURE ISSUES
Nigel Hampton,Application Manager - Power Cables
Borealis AB, Sweden.
ICC Fall 2003 Education Session
Content
� State of the artStress / thicknessService performanceDownsizing
� DesignTemperatureStrengthLengthAgeing
� ManufactureDegassingScorch
ICC Fall 2003 Education Session
Content
� State Of The ArtStress / ThicknessService PerformanceDownsizing
� DesignTemperatureStrengthLengthAgeing
� ManufactureMoistureDegassingScorchPurity
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)
Aver
age
wal
l thi
ckne
ss
(mm
)
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)
Core
Stre
ss (k
V/m
m)
HV
EHV
Mean & 90% Conf Limits
MV
ICC Fall 2003 Education Session
Selected HV Experience
0
500
1000
1500
2000
25 50 75 100 125 150 175VOLTAGE (kV)
CO
ND
UC
TOR
SIZ
E (S
QM
M)
Size Of Bubble Represents Length Of Installed Cores
ICC Fall 2003 Education Session
Thicknesses of Transmission Cables
0
5
10
15
20
25
1965 1970 1975 1980 1985 1990 1995 2000 2005
Thic
knes
s (m
m)
66 110 132 138 154
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)
Rel
ativ
e Va
lue
MATERIAL COST
WEIGHT
HV TECHNOLOGY6 / 3 kV/mm
EHV TECHNOLOGY9 / 6 kV/mm
1000SQMM, Pb SHEATH
ICC Fall 2003 Education Session
High Stress Gives Smaller Cables
>15% reduction in weight
5 - 10% reduction in material cost
ICC Fall 2003 Education Session
8
7
6
5
4
3
2
1
012
Wall thickness
Average stress
Volume
Requirement
14 16 18 20 22
Size Affects Electrical Requirement
Reference case - 2000mm2 150kVReference case - 2000mm2 150kV
ICC Fall 2003 Education Session
Content� State of the Art
Stress / ThicknessService PerformanceDownsizing
� DesignTemperatureStrengthLengthAgeing
� ManufactureMoistureDegassingScorchPurity
ICC Fall 2003 Education Session
Breakdown Stress - Design Stress
ICC Fall 2003 Education Session
Breakdown Stress - Design Stress
the winner of the 100mshould complete the marathon in 1 hour 10 mins
ICC Fall 2003 Education Session
Designing Cables
� Design Life� Size� Temperature� Safety
safetytempsizeage
breakdowndesign FFFF
EE =
ICC Fall 2003 Education Session
What Is The Outcome?
safetysizeage
temp@breakdowndesign FFF
EE =
ICC Fall 2003 Education Session
What Is The Outcome?
safetysizeage
temp@breakdowndesign FFF
EE =
40
2,22,2 - 3,8 1,1
ICC Fall 2003 Education Session
What Is The Outcome?
safetysizeage
temp@breakdowndesign FFF
EE =
mmThicknessmmkVEdesign 165.53/150/5.5
1.1*2.2*340
====
40
2,22,2 - 3,8 1,1
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)
Prob
abili
ty o
f fai
lure
50kV/mm33kV/mm
modeltransmissioncables
ICC Fall 2003 Education Session
115kV cables taken from service after 20 Years
UN USEDUSED
Slices Of Insulation Taken From Cables
ICC Fall 2003 Education Session
Endurance Curve - Transmission Cables
05
10152025303540
1,E+
00
1,E+
01
1,E+
02
1,E+
03
1,E+
04
1,E+
05
1,E+
06
Time (Hours)
Mea
n el
ectri
cal s
tress
(kV/
mm
)
FAIL ON TESTNO FAIL ON TESTNO FAIL IN SERVICE
LONG TERM TESTSLONG TERM TESTS
TYPETESTSTYPETESTS
ICC Fall 2003 Education Session
5mm25mm
Size
ICC Fall 2003 Education Session
0
10
20
30
40
50
60
70
10 100 1000 10000Length (m)
Elec
tric
Str
engt
h (k
V/m
m)
Size
5mm25mm
ICC Fall 2003 Education Session
Content
� State Of The ArtStress / ThicknessService PerformanceDownsizing
� DesignTemperatureStrengthLengthAgeing
� ManufactureMoistureDegassingScorchPurity
ICC Fall 2003 Education Session
Water / Moisture Remains A Concern
� Moisture Has ADramatic Effect OnAgeing
� Water Barrier HasTo Be Effective AndProtected
� Oversheaths &Jackets AreImportant Parts OfThe 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)
Mea
n El
ectri
cal S
tress
(k
V/m
m)
VIRGIN RAMP BREAKDOWNRAMP BREAKDOWN AFTER DRY AGEINGRAMP BREAKDOWN AFTER WET AGEING
ICC Fall 2003 Education Session
Dielectric Loss Measurements - HV Cable Models
0
10
20
30
0 20 40 60 80 100
Measuring Voltage (kV)
Tang
ent D
elta
(10E
-4) DEGAS 130C DEGAS 22C
AS MADE 130C AS MADE 22C
Industry Standard HV Insulation
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 o lierung in ppm
Ueb
erdr
uck
in b
ar
Overpressure at 90°C
Overpressure at 23°C
methane concentration in insulation in ppm
Ove
rpre
ssur
e in
bar
ICC Fall 2003 Education Session
Time taken for Degassing
0
5
10
15
20
25
30
5 10 15 20 25
Wall thickness (mm)
Deg
assi
ng ti
me
(day
s)
ICC Fall 2003 Education Session
0
0,5
1
1,5
2
2,5
as made max permitted long degassing GOAL FOR TOMORROW
Wei
ght L
oss
(%)
Degassing Data - TGA Method HD632
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
ICC Fall 2003 Education Session
“The Carrot Scorch Test”
Typical “Carrot”
Die
Scorch [vol-%]
Temperature [°C]
0125 130 135 140
20
40
60
80
∆SC=45%
∆T=8°C
- Effect of Temperature -Level and Sensitivity Effected
ICC Fall 2003 Education Session
By product concentration [WT%]
Time to critical scorch evolution [mins]
Increasing Run Length
Optimal Parameters For High Productivity
Decreasing Degassing Requirement
Today
Tomorrow
ICC Fall 2003 Education Session
CLEANLINESS - TAPE TESTSIZE
RANGE(MICRONS)
HVTECHNOLOGY
MVTECHNOLOGY
50 – 70 - -
70 –100 10 -
100 – 200 0 3
NUMBER AND SIZE ISNOT EVERYTHING!
HOW DO WE ALLOW FORDIFFERENT:
MATERIALSSHAPES
0
2
4
6
8
1 10 100
PERMITTIVITY
STRE
SS E
NHAN
CEM
ENT
FACT
OR
R/a=1R/a=0,1
WE NEED ASMARTER SET OFCRITERIA!!
ICC Fall 2003 Education Session
Electrical Stresses
0
2
4
6
8
0 5 10 15 20 25 30 35
Conductor stress (kV/mm)
Core
Stre
ss (k
V/m
m)
ICC Fall 2003 Education Session
Conclusions
� XLPE HV Cables have come a long way and have some exciting challenges ahead
� Much of the technology is well established and known
� Challenges for the futureuse of proven EHV technology to downsizelong lengthsincreased need
ATTENTION TO DETAIL → RELIABILITY