sheath bonding
DESCRIPTION
Cable boning method.TRANSCRIPT
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ICC C35D: Sheath Bonding of Multi-Conductor / Parallel Circuits
Cigr references with induced voltages, IEC 60287-3-1 Standard calculations, and EMF considerations Frdric LESUR
ICC Spring Meeting Seattle, March 2012
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Cigr Electra 128 Publication:
"Guide to the protection of specially bonded cable systems against sheath overvoltages"
Cigr WG B21.07, 1990 Revision of two previous Electra
publications (#28,1973 and #47, 1976) Main contents Types of sheath voltage limiter (SVL) in use Use of SVL Qualification tests for SVL Selection of SVL Insulation coordination + Appendix 2: Calculation of 50 Hz sheath
overvoltages due to system faults in a specially bonded cable system
C35D (Sheath Bonding of Multi-Conductor / Parallel Circuits): Cigr, IEC and general practices 2
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Cigr Technical Brochure 283
C35D (Sheath Bonding of Multi-Conductor / Parallel Circuits): Cigr, IEC and general practices 3
"Special bonding of high voltage power cables"
Cigr WG B1.18, 2005 Convener: Ray Awad (Canada) US Member: Mike Buckweitz
Main contents (106 pages) Power frequency applications
o 3.1.3 (power frequency impedance model) with methodology, structure of equation system, complex impedance matrix
Transient overvoltage applications Special considerations Recommendations
Can be downloaded at www.e-cigre.org (for free for Cigr members)
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Cigr Technical Brochure 347
C35D (Sheath Bonding of Multi-Conductor / Parallel Circuits): Cigr, IEC and general practices 4
"Earth potential rises in specially bonded screen systems"
Cigr TF B1.26, 2008 Convener: Eric Dorison (France) Canada Member: Yves Rajotte
Increasing number of configurations with underground cables inserted in overhead line systems (siphons) Assumption of low earth resistance at both
ends is no longer valid Earth potential rises in case of single-phase
fault cannot be neglected Main contents (98 pages) Calculation methods Typical situations Internal faults Worked examples
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IEC 60287-1-3 Standard
C35D (Sheath Bonding of Multi-Conductor / Parallel Circuits): Cigr, IEC and general practices 5
"Current sharing between parallel single-core cables and calculation of circulating current losses"
IEC, 2005 Main contents (49 pages) Scope Normative references Description of method Example calculations
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IEEE P575/D Draft Guide
C35D (Sheath Bonding of Multi-Conductor / Parallel Circuits): Cigr, IEC and general practices 6
"Draft guide for bonding shields and sheaths of single-conductor power cables rated 5 kV through 500 kV"
ICC C02W, work in progress Chair: Mike Buckweitz Annex F: Mohamed Chaaban
Main contents (80 pages) Shield optimization Special bonding techniques Sheath voltage limiters Effect on parallel communication and control
cables Current practice for shield/sheath standing
voltages Calculation of induced voltages Current and voltage distribution on cable
shields/sheaths with multiple cables per phase
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Cigr work in progress
WG B1.30 "Cable characteristics" Technical brochure will be published in 2012 Convener: Christian Royer (Canada) Canada Members: Yves Rajotte, Deepak Parmar (corresponding) US Member: Thomas Wilki
Main contents Definition of cable systems electrical characteristics Cable system types Formulae for cable systems electrical characteristics Measurement techniques Case studies
WG C4.502 "Power system technical performance issues related to the application of long HVAC cables"
Adequate modelling of AC cable lines, more focused on transients
C35D (Sheath Bonding of Multi-Conductor / Parallel Circuits): Cigr, IEC and general practices 7
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Double cable system model: IEEE P575/D11 figures
C35D (Sheath Bonding of Multi-Conductor / Parallel Circuits): Cigr, IEC and general practices 8
Figure F.1 - Example of 6 parallel cables; 2 cables per phase
Figure F.2Loops formed by the shields/sheaths of the installation
shown in figure F.1
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Equations and Kirchhoff's law
C35D (Sheath Bonding of Multi-Conductor / Parallel Circuits): Cigr, IEC and general practices 9
Phase R Phase S Phase T Sheaths Ground conductors
Voltages 1 p p+1 2p 2p+1 3p 3p+1 6p 6p+1 6p+q
Ph R V1 Z1,1 I1 Z1,2 I2 Z1,3 I3 Z1,4 I4 Z1,5 I5 Z1,6 I6 Z1,7 I7 Z1,8 I8 Z1,9 I9 Z1,10 I10 Z1,11 I11 Z1,12 I12 Z1,13 I13 Z1,14 I14
V2 Z2,1 I1 Z2,2 I2 Z2,3 I3 Z2,4 I4 Z2,5 I5 Z2,6 I6 Z2,7 I7 Z2,8 I8 Z2,9 I9 Z2,10 I10 Z2,11 I11 Z2,12 I12 Z2,13 I13 Z2,14 I14
Ph S V3 Z3,1 I1 Z3,2 I2 Z3,3 I3 Z3,4 I4 Z3,5 I5 Z3,6 I6 Z3,7 I7 Z3,8 I8 Z3,9 I9 Z3,10 I10 Z3,11 I11 Z3,12 I12 Z3,13 I13 Z3,14 I14
V4 Z4,1 I1 Z4,2 I2 Z4,3 I3 Z4,4 I4 Z4,5 I5 Z4,6 I6 Z4,7 I7 Z4,8 I8 Z4,9 I9 Z4,10 I10 Z4,11 I11 Z4,12 I12 Z4,13 I13 Z4,14 I14
Ph T V5 Z5,1 I1 Z5,2 I2 Z5,3 I3 Z5,4 I4 Z5,5 I5 Z5,6 I6 Z5,7 I7 Z5,8 I8 Z5,9 I9 Z5,10 I10 Z5,11 I11 Z5,12 I12 Z5,13 I13 Z5,14 I14
V6 Z6,1 I1 Z6,2 I2 Z6,3 I3 Z6,4 I4 Z6,5 I5 Z6,6 I6 Z6,7 I7 Z6,8 I8 Z6,9 I9 Z6,10 I10 Z6,11 I11 Z6,12 I12 Z6,13 I13 Z6,14 I14
Sheaths
V7 Z7,1 I1 Z7,2 I2 Z7,3 I3 Z7,4 I4 Z7,5 I5 Z7,6 I6 Z7,7 I7 Z7,8 I8 Z7,9 I9 Z7,10 I10 Z7,11 I11 Z7,12 I12 Z7,13 I13 Z7,14 I14
V8 Z8,1 I1 Z8,2 I2 Z8,2 I2 Z8,4 I4 Z8,5 I5 Z8,6 I6 Z8,7 I7 Z8,8 I8 Z8,9 I9 Z8,10 I10 Z8,11 I11 Z8,12 I12 Z8,13 I13 Z8,14 I14
V9 Z9,1 I1 Z9,2 I2 Z9,3 I3 Z9,4 I4 Z9,5 I5 Z9,6 I6 Z9,7 I7 Z9,8 I8 Z9,9 I9 Z9,10 I10 Z9,11 I11 Z9,12 I12 Z9,13 I13 Z9,14 I14
V10 Z10,1 I1 Z10,2 I2 Z10,3 I3 Z10,4 I4 Z10,5 I5 Z10,6 I6 Z10,7 I7 Z10,8 I8 Z10,9 I9 Z10,10 I10 Z10,11 I11 Z10,12 I12 Z10,13 I13 Z10,14 I14
V11 Z11,1 I1 Z11,2 I2 Z11,3 I3 Z11,4 I4 Z11,5 I5 Z11,6 I6 Z11,7 I7 Z11,8 I8 Z11,9 I9 Z11,10 I10 Z11,11 I11 Z11,12 I12 Z11,13 I13 Z11,14 I14
V12 Z12,1 I1 Z12,2 I2 Z12,3 I3 Z12,4 I4 Z12,5 I5 Z12,6 I6 Z12,7 I7 Z12,8 I8 Z12,9 I9 Z12,10 I10 Z12,11 I11 Z12,12 I12 Z12,13 I13 Z12,14 I14
Ground conductors
V13 Z13,1 I1 Z13,2 I2 Z13,3 I3 Z13,4 I4 Z13,5 I5 Z13,6 I6 Z13,7 I7 Z13,8 I8 Z13,9 I9 Z13,10 I10 Z13,11 I11 Z13,12 I12 Z13,13 I13 Z13,14 I14
V14 Z14,1 I1 Z14,2 I2 Z14,3 I3 Z14,4 I4 Z14,5 I5 Z14,6 I6 Z14,7 I7 Z14,8 I8 Z14,9 I9 Z14,10 I10 Z14,11 I11 Z14,12 I12 Z14,13 I13 Z14,14 I14
Currents
IR [ ] I1 I2
IS [ ] I3 I4
IT [ ] I5 I6
[ ] I7 I8 I9 I10 I11 I12 I13 I14
Example of 6 parallel cables (2 cables per phase, p = 2) and 2 ground continuity conductors (q = 2)
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Methodology
Prepare the symmetric matrix Sort the Zi,jIj for conductors connected to the same phase (RST or ABC),
sheaths and ground continuity conductors Calculate the impedances Zi,jIj Matrix is symmetric (mutual influence of metallic conductors, value linked to the axial
distance between metallic conductors di,j = dj,i)
Subtract two adjacent rows of same voltage drop V Leading to Zi,jIj - Zi+1,jIj = 0
Write equations of currents of conductor loops Ik = IR, respectively Is and IT
Write equation of currents of sheaths and grounded conductors Ik = 0
Solve the equation system [Q]=[Z][I] With classical matrix algebra [I]=[Z]-1[Q] Unique solution, no iterative converging process
C35D (Sheath Bonding of Multi-Conductor / Parallel Circuits): Cigr, IEC and general practices 10
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Calculation of impedances
General formula of mutual impedance between two metallic conductors (i,j)
Applied to cores, shields/sheaths, ground continuity conductors, per unit length
: angular frequency of system (2f), [s-1] 0 : magnetic permeability of free space = 4.10-7, [H/m] D : distance to earth return fictitious path by an equivalent conductor
o No need to be calculated, is eliminated by the subtraction of two adjacent rows Self resistance Ri,i= AC resistance of conductor (i=j) Mutual resistance Ri,j= 0 (ij)
Subtraction of two adjacent rows D is eliminated
C35D (Sheath Bonding of Multi-Conductor / Parallel Circuits): Cigr, IEC and general practices 11
+
+=+
+=ji,
00ji,ji,
0ji,ji, d
Dln
2
j8
RXj8
RZ
=
= +
++
ji,
j1,i7-
j1,i
0
ji,
0j1,iji, d
dln10.2
dD
ln2
dD
ln2
XX
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Calculation of inductances
Special cases (on the matrix diagonal) Self inductance of the conductor
dc : diameter of the conductor [mm] : coefficient depending on the construction of the conductor, to represent the mean
radius of the core (see Table 1 in IEC 60287-1-3 + annex for hollow cores) Self inductance of the sheath
ds : mean diameter of the shield/sheath [mm]
Self inductance of the ground continuity conductor Same expression for Xg than for Xc with dg instead of dc
Mutual impedance between conductor and shield of the same cable Involves mean distance between core and sheath Same expression for Xi,j than for Xs with mean diameter of sheath ds
C35D (Sheath Bonding of Multi-Conductor / Parallel Circuits): Cigr, IEC and general practices 12
=
+
=c
0
c
0c d
Dln
2
d2D
41
ln2
X
=s
0s d
Dln
2
X s(outer)s(inner)s .ddd =
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Calculation of loss factor
IEC 60287-1-3 Standard
C35D (Sheath Bonding of Multi-Conductor / Parallel Circuits): Cigr, IEC and general practices 13
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IEC 60287-1-3 example 1
More digits to check your own calculation tool Results: magnitude (A) and angle of currents I, and sheath loss factor 'p
C35D (Sheath Bonding of Multi-Conductor / Parallel Circuits): Cigr, IEC and general practices 14
1) (x,y) = 0.0000 ; -1.0000 ; Icalc -> 50.0000 (A) / 0.00 ph[0] Icalc -> 28.7177 (A) / -138.79 lambda1 = 2.0362 2) (x,y) = 0.2000 ; -1.0000 ; Icalc -> 50.0000 (A) / -120.00 ph[1] Icalc -> 25.2974 (A) / 121.16 lambda1 = 1.5800 3) (x,y) = 0.4000 ; -1.0000 ; Icalc -> 50.0000 (A) / 120.00 ph[2] Icalc -> 34.8026 (A) / -4.50 lambda1 = 2.9905 4) (x,y) = 0.6000 ; -1.0000 ; Icalc -> 50.0000 (A) / 120.00 ph[2] Icalc -> 34.8026 (A) / -4.50 lambda1 = 2.9905 5) (x,y) = 0.8000 ; -1.0000 ; Icalc -> 50.0000 (A) / -120.00 ph[1] Icalc -> 25.2974 (A) / 121.16 lambda1 = 1.5800 6) (x,y) = 1.0000 ; -1.0000 ; Icalc -> 50.0000 (A) / 0.00 ph[0] Icalc -> 28.7177 (A) / -138.79 lambda1 = 2.0362
IEC 60287-1-3 Results
-1 0 1 2 3
-1,00
1,00
Laying depth = 1.0 m Axial distance between conductors = 0.20 m
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IEC 60287-1-3 example 1
C35D (Sheath Bonding of Multi-Conductor / Parallel Circuits): Cigr, IEC and general practices 15
T1,T2
T1s, T2s
S1, S2
S1s, S2s
R1, R2
R1s, R2s
-50
-40
-30
-20
-10
0
10
20
30
40
50
-50 -40 -30 -20 -10 0 10 20 30 40 50-1 0 1 2 3
-1,00
1,00
Laying depth = 1.0 m Axial distance between conductors = 0.20 m
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Influence of phase rotation (example 1 rotation reversed) Results: magnitude (A) and angle of currents I, and sheath loss factor 'p
IEC 60287-1-3 example 2
C35D (Sheath Bonding of Multi-Conductor / Parallel Circuits): Cigr, IEC and general practices 16
1) (x,y) = 0,0000 ; -1,0000 ; Icalc -> 50,0000 (A) / 0,00 ph[0] Icalc -> 34,3695 (A) / -122,59 lambda1 = 2,9165 2) (x,y) = 0,2000 ; -1,0000 ; Icalc -> 50,0000 (A) / 120,00 ph[2] Icalc -> 24,4600 (A) / -0,91 lambda1 = 1,4772 3) (x,y) = 0,4000 ; -1,0000 ; Icalc -> 50,0000 (A) / -120,00 ph[1] Icalc -> 29,9388 (A) / 101,45 lambda1 = 2,2130 4) (x,y) = 0,6000 ; -1,0000 ; Icalc -> 50,0000 (A) / -120,00 ph[1] Icalc -> 29,9388 (A) / 101,45 lambda1 = 2,2130 5) (x,y) = 0,8000 ; -1,0000 ; Icalc -> 50,0000 (A) / 120,00 ph[2] Icalc -> 24,4600 (A) / -0,91 lambda1 = 1,4772 6) (x,y) = 1,0000 ; -1,0000 ; Icalc -> 50,0000 (A) / 0,00 ph[0] Icalc -> 34,3695 (A) / -122,59 lambda1 = 2,9165
IEC 60287-1-3 Results
-1 0 1 2 3
-1,00
1,00
Laying depth = 1.0 m Axial distance between conductors = 0.20 m
Same data as example 1, phase rotation has been reversed
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T1,T2
T1s, T2s
S1, S2
S1s, S2s
R1, R2
R1s, R2s
-50
-40
-30
-20
-10
0
10
20
30
40
50
-50 -40 -30 -20 -10 0 10 20 30 40 50
IEC 60287-1-3 example 2
C35D (Sheath Bonding of Multi-Conductor / Parallel Circuits): Cigr, IEC and general practices 17
-1 0 1 2 3
-1,00
1,00
Laying depth = 1.0 m Axial distance between conductors = 0.20 m
Same data as example 1, phase rotation has been reversed
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IEC 60287-1-3 example 3
Trefoil formation leads to balanced currents Results: magnitude (A) and angle of currents I, and sheath loss factor 'p
C35D (Sheath Bonding of Multi-Conductor / Parallel Circuits): Cigr, IEC and general practices 18
1) (x,y) = 0,0000 ; -1,0000 ; Icalc -> 50,0000 (A) / -120,00 ph[1] Icalc -> 13,7617 (A) / 134,48 lambda1 = 0,4676 2) (x,y) = 0,0300 ; -0,9480 ; Icalc -> 50,0000 (A) / 0,00 ph[0] Icalc -> 13,8587 (A) / -107,03 lambda1 = 0,4742 3) (x,y) = 0,0600 ; -1,0000 ; Icalc -> 50,0000 (A) / 120,00 ph[2] Icalc -> 14,1229 (A) / 14,06 lambda1 = 0,4925 4) (x,y) = 0,2000 ; -1,0000 ; Icalc -> 50,0000 (A) / 120,00 ph[2] Icalc -> 14,1229 (A) / 14,06 lambda1 = 0,4925 5) (x,y) = 0,2300 ; -0,9480 ; Icalc -> 50,0000 (A) / 0,00 ph[0] Icalc -> 13,8587 (A) / -107,03 lambda1 = 0,4742 6) (x,y) = 0,2600 ; -1,0000 ; Icalc -> 50,0000 (A) / -120,00 ph[1] Icalc -> 13,7617 (A) / 134,48 lambda1 = 0,4676
IEC 60287-1-3 Results
-1 0 1 2 3
-0,98
1,00
Bottom trench laying depth = 1.0 m Axial distance between conductors = 0.06 m
Trefoil formation
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-1 0 1 2 3
-0,98
1,00
Bottom trench laying depth = 1.0 mAxial distance between conductors = 0.06 m
Trefoil formation
T1,T2
T1s, T2s
S1, S2
S1s, S2s
R1, R2
R1s, R2s
-50
-40
-30
-20
-10
0
10
20
30
40
50
-50 -40 -30 -20 -10 0 10 20 30 40 50
IEC 60287-1-3 example 3
C35D (Sheath Bonding of Multi-Conductor / Parallel Circuits): Cigr, IEC and general practices 19
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Conductors of one phase placed together (flat as example 1) Results: magnitude (A) and angle of currents I, and sheath loss factor 'p
IEC 60287-1-3 example 4
C35D (Sheath Bonding of Multi-Conductor / Parallel Circuits): Cigr, IEC and general practices 20
1) (x,y) = 0,0000 ; -1,0000 ; Icalc -> 46,3082 (A) / 1,13 ph[0] Icalc -> 38,3598 (A) / -149,88 lambda1 = 4,2354 2) (x,y) = 0,8000 ; -1,0000 ; Icalc -> 44,5950 (A) / -124,53 ph[1] Icalc -> 37,4186 (A) / 105,13 lambda1 = 4,3457 3) (x,y) = 1,6000 ; -1,0000 ; Icalc -> 50,7573 (A) / 115,11 ph[2] Icalc -> 43,7042 (A) / -20,53 lambda1 = 4,5762 4) (x,y) = 0,4000 ; -1,0000 ; Icalc -> 53,7086 (A) / -0,98 ph[0] Icalc -> 36,4617 (A) / -150,17 lambda1 = 2,8448 5) (x,y) = 1,2000 ; -1,0000 ; Icalc -> 55,6564 (A) / -116,37 ph[1] Icalc -> 34,8476 (A) / 101,88 lambda1 = 2,4198 6) (x,y) = 2,0000 ; -1,0000 ; Icalc -> 49,6166 (A) / 125,00 ph[2] Icalc -> 44,4178 (A) / -23,21 lambda1 = 4,9468
IEC 60287-1-3 Results
0 1 2 3 4
-1,00
1,00
Laying depth = 1.0 m Axial distance between conductors = 0.40 m
Same geometry as example 1, Conductors of one phase placed together
current sharing between phase
conductors is not equal,
sheath losses for this cable arrangement are
very high,
This arrangement must be avoided
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R1
R1s
S1
S1s
T1
T1s
T2
T2s
S2
S2s
R2
R2s
-60
-40
-20
0
20
40
60
-40 -30 -20 -10 0 10 20 30 40 50 60
IEC 60287-1-3 example 4
C35D (Sheath Bonding of Multi-Conductor / Parallel Circuits): Cigr, IEC and general practices 21
0 1 2 3 4
-1,00
1,00
Laying depth = 1.0 mAxial distance between conductors = 0.40 m
Same geometry as example 1,Conductors of one phase placed together
current sharing between phase
conductors is not equal,
sheath losses for this cable arrangement are
very high,
This arrangement must be avoided
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Electromagnetic Field 50 Hz
x-distance from axis power line (m)11109876543210-1-2-3-4-5-6-7-8-9
Max
Fie
ld rm
s (
T)
0,5
0,45
0,4
0,35
0,3
0,25
0,2
0,15
0,1
0,05
0
EMF mitigation technique: shields/sheaths make a passive loop to compensate the magnetic field
Example 1 of IEC 60287-1-3 Shielding factor SF = 1.44
C35D (Sheath Bonding of Multi-Conductor / Parallel Circuits): Cigr, IEC and general practices 22
Laying depth = 1.0 m Axial distance between conductors = 0.20 m MF calculated 1 m above ground surface, with (red) and without (blue) solid bonding,
I = 50 A in each cable
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Work in progress
C35D (Sheath Bonding of Multi-Conductor / Parallel Circuits): Cigr, IEC and general practices 23
Features IEC 60287-1-3 Current tool
number of circuits in parallel 2 n 1
number of phases 3 (RST or ABC) multiple of 3 (possibility of
independent circuits)
number of ground continuity conductors 0 q 0
3 and 2-phase circuits mixed in parallel no
other grounding mode than solid bonding no
single bonding (calculation of induced
voltages)
coupling with EMF calculations no yes
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Further work for next ICC Meeting
ICC Fall Meeting in Saint Pete (FL), November 2012 Presentation of new case studies Parallel independent circuits (connected to different busbars with different current
ratings) Single bonded circuits and calculation of induced voltages
Call for worked examples! Send to [email protected]
Future prospects Transposed conductors Crossbonded shields/sheaths Transposed ground continuity conductors
C35D (Sheath Bonding of Multi-Conductor / Parallel Circuits): Cigr, IEC and general practices 24