ABB AB High Voltage Cables, Danijela Palmgren, Växjö 23 April, 2013
Armour loss in three-core
submarine XLPE cables
© ABB Group
April 24, 2013 | Slide 1
Content

Introduction to ABB and Cable Design

Armour losses in three-core cables:
• Measurement method
• Test object
• Measurement equipment
• Measurement accuracy
• Measurement results

© ABB Group
April 24, 2013 | Slide 2
Summary
ABB
Cable Business within ABB
ABB Kabeldon, Alingsås
ABB AB, Karlskrona
ABB Huntersville
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April 24, 2013 | Slide 3
ABB
ABB AB - High Voltage Cables
High Voltage Cables
Finland
Norway
Sweden
Karlskrona
Great
Britain
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April 24, 2013 | Slide 4
•
One of the world’s most modern cable factories
•
Standard cables and advanced customized products
•
Extruded and paper insulated cables for both AC and DC
•
Submarine and underground high voltage turn key projects
ABB
HVAC Cable Design: Land
Conductor
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April 24, 2013 | Slide 5
Conductor
screen
Insulation
Insulation
screen
Bedding
Bedding
Metal screen
Bedding
Metal sheath
Outer sheath
ABB
HVAC Cable Design: Submarine Single Core
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April 24, 2013 | Slide 6
ABB
HVAC Cable Design: Submarine Three-Core
Metal sheath
Inner plastic sheath
Conductor
Conductor shield
Insulation
Profiles
Insulation shield
Armour
Outer sheath (Polypropylene yarn)
© ABB Group
April 24, 2013 | Slide 7
Optical fiber
ABB
Armour loss calculations acc. to IEC 60287

Three-core SL type cables – steel wire armour:
Where:
RA
R
Rs
X
c
dA
© ABB Group
April 24, 2013 | Slide 8
the ac resistance of armour at maximum armour temperature (ohm/m)
ac resistance of conductor at maximum operting temperature (ohm/m)
resistance of sheath or screen per unit length of cable at its maximum operting temperture (ohm/m)
reactance per unit length of sheath or screen per unit length of cable (ohm/m)
the distance between the axis of a conductor and the cable centre (mm)
mean diameter of armour (mm)
ABB
Armour loss calculations acc. to IEC 60287

The equations for armour loss calculations according to IEC 60287 probably
originate from measurements performed 1939 by ERA

The equations are semi-empirical

The equation has been derived from measurements performed on several
cables

All cables were relatively small. The largest test cable was 1in2 (approx. 689
mm2)

All test cables had a common metal sheath

The accuracy of the measurement equipment has significantly been improved
since 1939

Having in mind the typical cable design for three-core submarine cables of
today, their ever-increasing size and the improved measurement accuracy the
correctness of the equations for calculation of armour loss in three-core cables
has been questioned
© ABB Group
April 24, 2013 | Slide 9
ABB
Armour loss measurement: Measurement method
 Three-phase transformer with connection group Dyn11 connected to
a symmetrical 400 V network
 Transformation performed on the primary side
 Connection leads between the transformer and the test object were
equal in length, bundled and kept as short as possible
 The cable cores at the ends of the test object were kept as short as
possible
 The test object was long, i.e. 75 and 59 m
 The test object was laid on wooden trestles
 The cable was heated only during the measurements
 The measurements were performed at four current steps
 The measured losses are the total cable losses
 The armour losses are calculated by subtracting the conductor and
sheath losses from the total cable losses
© ABB Group
April 24, 2013 | Slide 10
ABB
Armour loss measurement: Three-core cable designs
Rated voltage
Max. system voltage
115 kV
123 kV
Conductor
Type/material
Cross-section
Diameter
solid copper
240 mm²
17,5 mm
Insulation system
Material 1
Material 2
Material 3
semi-conductive PE
XLPE
semi-conductive PE
Metallic sheath
Type/material
Thickness
Diameter
lead alloy
2 mm
56 mm
Inner sheath
Type/material
Diameter
Optical cable
PE
60 mm
Armouring
Type
Material 1
Material 2
Wire diameter
Diameter
Outer cover
Material
Complete cable
Diameter
© ABB Group
April 24, 2013 | Slide 11
132 kV
145 kV
Conductor
Type/material
Cross-section
Diameter
compacted aluminium
815 mm²
35 mm
Insulation system
Material 1
Material 2
Material 3
semi-conductive PE
XLPE
semi-conductive PE
Metallic sheath
Type/material
Thickness
Diameter
lead alloy
2 mm
77 mm
Inner sheath
Type/material
Diameter
Optical cable
PE
81 mm
Cable assembly
Cable assembly
Bedding
Type/material
Rated voltage
Max. system voltage
polymeric tapes
Double armour
Galvanized steel (72+84
wires)
Bitumen
5 mm
151 mm
Polypropylene yarn
159 mm
Bedding
Type/material
polymeric tapes
Armouring
Type
Material 1
Material 2
Material 3
Wire diameter
Diameter
Single armour
Galvanized steel (64 wires)
PR/Polyester wire (64 wires)
Bitumen
4 mm
183 mm
Outer cover
Material
Polypropylene yarn
Complete cable
Diameter
191 mm
ABB
Armour loss measurement: Measurement equipment
© ABB Group
April 24, 2013 | Slide 12
ABB
Armour loss measurement: Armoured cable
© ABB Group
April 24, 2013 | Slide 13
ABB
Armour loss measurement: Unarmoured cable
© ABB Group
April 24, 2013 | Slide 14
ABB
Armour loss measurement: Measurement accuracy
The armour loss for the single layer armour design is calculated according to:
Where:
The relative error of the armour loss is:
Wm1
Ic1
Is1
Rc1
Rs1
Wm1
Measured cable losses
Measured conductor current
Measured sheath current
Measured conductor resistance
Measured sheath resistance
The sum of all errors of the
measured values
To improve the accuracy a difference method is chosen:
Index 0
Index 1
The armour loss can be calculated as :
© ABB Group
April 24, 2013 | Slide 15
unarmoured cable
armoured cable
The error is minimized
ABB
Armour loss measurement: Results
Double wire armour design:
Double armour – no armour
Ic2
[A]
303,5
402,6
600,1
789,0
c2 [C]
13,3
13,3
16,7
10,6
1 [p.u.]
0,0992 0,1001 0,0998 0,1076
2 [p.u.]
0,0655 0,0700 0,0779 0,0712
Correction to 90 C conductor temperature
c2 [C]
90
90
90
90
2 [p.u.]
0,0500 0,0535 0,0603 0,0538
Single armour – no armour
Ic1
c1
1
2
[A]
304,9
404,3
600,4
799,0
[C]
14,1
13,2
14,7
10,7
[p.u.] 0,0966 0,0985 0,1007
0,1043
[p.u.] 0,0597 0,0675 0,0816
0,0859
Correction to 90 C conductor temperature
c1
[C]
90
90
90
90
2 [p.u.] 0,0457 0,0515 0,0627
0,0649
© ABB Group
April 24, 2013 | Slide 16
ABB
Armour loss measurement: Results
Single wire armour design:
Single armour – no armour
Ic1
c1
1
2
c1
2
© ABB Group
April 24, 2013 | Slide 17
[A]
326,1
431,9
640,7
846,7
[C]
16,8
17,0
17,9
15,1
[p.u.]
0,1653 0,1680 0,1739 0,1798
[p.u.]
0,1132 0,1355 0,1609 0,1870
Correction to 90 C conductor temperature
[C]
90
90
90
90
[p.u.]
0,0872 0,1044 0,1245 0,1430
ABB
Armour loss measurement: Summary
 The test object must be sufficiently long.
 The measurement must be performed at rated current.
 Measurements need to be performed on cable with and without armour.
 The measurement accuracy is increased by means of the difference method.
 The measurement indicates no difference between single and double armoured
cable.
 The armour loss calculated according to IEC 60287 is much larger than the
armour loss calculated out of the measured data.
 The quote between the sheath loss factor for an armoured SL type three-core
cable and the sheath loss factor for an unarmourd SL type cable according to IEC
60287 is 1.5. The measurements for the single wire armour design show a factor
between 1.3-1.5, while for the double wire armour design the factor is 1.7-1.9.
© ABB Group
April 24, 2013 | Slide 18
ABB
Last but not least …
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April 24, 2013 | Slide 19
ABB
Thank you!
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April 24, 2013 | Slide 20