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Grounding Tutorial
Substation Ground System Design & Standard IEEE 80
Terry Klimchack
Revised 03/10/14
ERICO has met the standards and requirements of the Registered
Continuing Education Providers Program. Credit earned on completion of
this program will be reported to RCEPP. A certificate of completion will be
issued to each participant. As such, it does not include content that may
be deemed or construed to be an approval or endorsement by NCEES or
RCEPP.”
Copyrighted Materials
This educational activity is protected by copyright laws. Reproduction, distribution, display and use of the educational activity without written permission of the
presenting sponsor is prohibited.
Copyright ERICO International Corporation, 2014
Presentation Outline
• Grounding System Design Theory• Grounding System Design Example• Grounding System Components• Questions
Grounding System Design Theory
Today’s Challenges• Power plans and substations are operating past their original
design service life• Engineers and designers are faced with rising fault currents
requirements
Theoretical Conditions (Assumes Homogeneous Environment)
Actual Field Conditions (Non-Homogeneous Environment)
Illustration of substation ground potential rise equipotential lines
Wenner’s or Four Pin Method
I
VR
aR
la
a
la
aaR 2
4
21
4
2222
1
2
Fall of Potential Method or 3PM
)2
ln(
2
1)8
ln(
2
a
llR
d
llR
I
VR
1
2
Principle: RPrinciple: RE E 3pole3pole
Maximum Theoretical Accuracy
LEAD LENGTH MAXIMUM THEORETICAL ACCURACY
2L 50%
4L 75%
8L 87.5%
16L 93.7%
32L 96.8%
L= radial ground mat dimension
Basic Shock Situation
Touch Potential
• Touch Potential is the potential difference between GPR and the surface potential at the point where a person is standing, while at the same time having hands in contact with a grounded structure
• Touch Potential is controlled by proper bonding and protective systems, such as personnel safety mats.
Touch Potential
• 1,000A Fault current • 5Ω Ground resistance
5,000 V
• Touch potential due to voltage gradient2,500 V
• Resistance of body: 1,000 Ω (IEEE® 80)
2.5A Current2,500V
IEEE is a registered trademark of The Institute of Electrical and Electronics Engineers, Inc.
Touch Potential
Same potential as towerNo protection
Step Potential
• Step Potential is the difference in surface potential experienced by a person’s feet bridging a distance of 1m without contacting any other grounded surface.
• Step Potential is controlled by properly designed ground electrode system (grid) or the use of wire mesh.
Step Potential
50% Voltage Dropbetween feet
Same potential between feet
Tolerable Voltages
Touch Voltage Step Voltage
Where
Estep is the step voltage in V
Etouch is the touch voltage in V
Cs is determined from figure or equation
s is the resistivity of the surface material in -m
ts is the duration of shock current in seconds
If no protective surface layer is used, then Cs =1 and s = .
s
sstoucht
CE116.0
5.1100050
s
sstoucht
CE157.0
5.1100070
s
ssstept
CE116.0
6100050
s
ssstept
CE157.0
6100070
Dalziel’s Equations
Tolerable Body Current Limits
for 50 kg body weight
for 70 kg body weight
ts time in seconds
s
Bt
I116.0
s
Bt
I157.0
Body Current Versus Time
C-Curves (Cs versus hs)
Chs
s
s
1
0 09 1
2 0 09
.
.
Cs = surface layer rerating factor hs = thickness of the surface material
Conductor Equations
where
I is the rms current in Ka
Amm2 is the conductor cross section in mm2
Tm is the maximum allowable temperature in oC
Ta is the ambient temperature in oC
Tr is the reference temperature for material constants in oC
o is the thermal coefficient of resistivity at 0oC in 1/oC
r is the thermal coefficient of resistivity at reference temperature Tr in 1/oC
r is the resistivity of the ground conductor at reference temperature Tr in -cm
Ko 1/o or (1/r) - Tr in oC
tc is the duration of current in s
TCAP is the thermal capacity per unit volume from table 11-1, in J/(cm3·oC)
ao
mo
rrcmm TK
TK
t
TCAPAI ln
10 4
2
Ultimate Current Carrying Capabilities of Copper Conductors
Currents are RMS values, for frequency of 60 Hz, X/R = 40
Current in kilo-amperes
CableSize,
AWG
Nominal Cross
Section, mm2
6 cycles(100 ms)
15 cycles(250 ms)
30 cycles(500 ms)
45 cycles(750 ms)
60 cycles(1 s)
180 cycles(3 s)
#2 33.63 22 16 12 10 9 5
#1 42.41 28 21 16 13 11 7
1/0 53.48 36 26 20 17 14 8
2/0 67.42 45 33 25 21 18 11
3/0 85.03 57 42 32 27 23 14
4/0 107.20 72 53 40 34 30 17
250kcmil
126.65 85 62 47 40 35 21
350kcmil
177.36 119 87 67 56 49 29
Grounding System Design Example
Substation Design Flowchart
Step 1 - Parameters
• Ground fault current to the grid on 13 kV bus = 3,180 A.• Fault duration tf = 0.5 s• Soil resistivity ρ= 400 Ωm• Wet crushed rock resistivity ρs = 2.500 Ωm
• Thickness of crushed rock hs = 0.1 m• Depth of grid burial h = 0.5 m• Available grounding area 70m x 70m• Area occupied be the grid 4,900 m2
Step 1 - Parameters
Current deviation factor Sf = 0.6
Step 2 – Fault Current & Conductor Size
Ignoring the station resistance, the symmetrical ground fault current on 115 kV
IE
R R R R j X X Xf0
1 2 0 1 2 03
( ) ( )
A
jI 3180
0.400.100.100.100.40.403
3000,115)3(3 0
For the 13 kV bus fault, the 115 kV equivalent fault impedances must be transferred to the 13 kV side of 1 the transformer. It should be noted that, due to the delta-wye connection of the transformer, only the 2 positive sequence 115 kV fault impedance is transferred. Thus 3
142.1085.0014.1034.00.100.4115
132
1 jjjZ
Z j0 0 034 1 014 . .
Amps
jI 814,6
014.1142.1142.1034.0085.0085.0)0(3
3000,13)3(3 0
Conductor size
A I K tkcmil f c
kcmilkcmilAkcmil 02.3402.345.006.7814.6
The 34.02 kcmil is approximately #4 AVG. To increase service life 2/0 is recommended.
Step 2 – Fault Current & Conductor Size
Decrement factor Df is approximately1.0; thus, the rms asymmetrical fault current is also 6814 A
Step 3 – Step and Touch Potentials
For 0.1 m (4 in) layer of surface material, with a wet resistivity of 2500 Ω·m, and for an earth with resistivity of 400 Ω·m.
74.009.0)102.0(2
2500
400109.0
09.02
109.0
1
s
ss h
C
Reduction factor
E C tstep s s s70 1000 6 0157 . / 6.26865.0157.0250074.061000
ssstouch tCE /157.05.1100070 2.8385.0157.0250074.05.11000
Step 4 - Initial Design
Assume a preliminary layout of 70 m × 70 m grid with equally spaced conductors, with spacing D = 7 m, grid burial depth h = 0.5 m, and no ground rods. The total length of buried conductor, LT, is 2 × 11 × 70 m = 1540 m.
Step 5 -Determination of Grid Resistance
For L = 1540 m, and grid area A = 4900 m2, the resistance is
RL A h A
gT
1 1
201
1
1 20 /
R ohmsg
400
1
1540
1
20 49001
1
1 0 5 20 49002 78
..
Step 6 - Maximum grid current Ig Given from Step 2 – Df = 1.0, and Sf = 0.6
SI
Ifg
o
3
I D IG f g
Though the 13 kV bus fault value of 6814 A is greater than the 115 kV bus fault value of 3180 A, The wye-grounded 13 kV transformer winding is a “local” source of fault current and does not contribute to the GPR. Thus, the maximum grid current is based on 3180 A.
I D S IG f f 3 0
AIG 190831806.01
Step 7 - Ground Potential Rise GPR
Now it is necessary to compare the product of IG and Rg, or GPR, to the tolerable touch voltage, Etouch70
Since GPR = 5,304 V far exceeds Etouch70 = 838 V (determined in Step 3) as the safe value, additional design evaluations are necessary.
GPR I RG g
GPR volts 1908 2 78 5304.
Step 8 - Mesh Voltage
12
8ln
48
2
16ln
2
1 22
nK
K
d
h
dD
hD
dh
DK
h
ii
m
n
ii
nK
2
2
1
57.0
112
1112
0
1h
hK h 225.1
0.1
5.01
89.0
1112
8ln
225.1
57.0
01.04
5.0
01.078
5.027
01.05.016
7ln
2
1 22
mK
nK i 148.0644.0
p
Ca L
Ln
211
280
15402
nb = 1 for square grid nc = 1 for square grid nd = 1 for square grid and therefore
RC
imGm LL
KKIE
volts1.10021540
272.289.01908400
n = na ⋅nb ⋅nc ⋅nd 111*1*1*11
272.211148.0644.0
Step 9 - Em vs. Etouch
• The mesh voltage 1002.1 V is higher than the tolerable touch voltage 838.2 V. The grid design must be modified.
• There are two approaches to modifying the grid design to meet the tolerable touch voltage requirements: – Reduce the GPR to a value below the tolerable touch
voltage or to a value low enough to result in a value of Em below the tolerable touch voltage
– Reduce the available ground fault current
Modified DesignIn this example, the preliminary design will be modified to include 20 ground rods, each 7.5 m (24.6 ft) long, around the perimeter of the grid.
Repeating Step 5• Using Equation for LT = 1540 + 20 • 7.5 = 1690 m, and A =
4900 m2 yields the following value of grid resistance Rg:
• Steps 6 and 7. The revised GPR is (1908)(2.75) = 5247 V, which is still much greater than 838.2 V.
AhAL
RT
g/201
11
20
11 ohms75.24900205.01
11
490020
1
1690
1400
The step voltage has not been calculated yet, the new values of Ki, Es, LS, and Ks have to be also calculated. Note that the value for Ki is still 2.272 (same as for mesh voltage).
Repeating Step 8
12
8ln
48
2
16ln
2
1 22
nK
K
d
h
dD
hD
dh
DK
h
ii
m
Kii = 1.0 with
rods 0
1h
hK h 225.1
0.1
5.01
77.0
1112
8ln
225.1
0.1
01.04
5.0
01.078
5.027
01.05.016
7ln
2
1 22
mK
R
G
LLL
LL
KKIE
yx
rC
imm
2222.155.1
volts4.747
1507070
5.722.155.11540
272.277.01908400
22
Final Design
• Step 9: Em vs. Etouch. Now the calculated corner mesh voltage is lower than the tolerable touch voltage (747.4 V versus 838.2 V), and we are ready to proceed to Step 10.
• Step 10: Es vs. Estep. The computed Es is well below the tolerable step voltage determined in Step 3 of the initial design. That is, 548.9 V is much less than 2686.6 V.
• Step 11: Modify design. Not necessary for this example. • Step 12: Detailed design. A safe design has been obtained. At this point, all
equipment pigtails, additional ground rods for surge arresters, etc., should be added to complete the grid design details.
25.01
11
2
11 ns DhDh
K
406.05.017
1
5.07
1
5.02
11 211
RC
isGs LL
KKIE
85.075.0
volts9.548
15085.0154075.0
272.2406.01908400
Other Areas of Concern• Substation Fences
Fence grounding is of major importance because the fence is usually accessible to the general public.The NESC requires grounding metal fences used to enclose electric supply substations having energized conductors or equipment.
• Gravel New studies are available on the Resistivity of various crushed gravel
Fence and Gate Jumpers
Same Design Parameters
Using Software
Computer Software Calculations
Single Phase Voltage or Current Source Accept
Cancel
Voltage Source
Current Source
Single Phase Current Source (3.18 kA)
SOURCE_A
Circuit Number 1
Current (kA)
3.18
First Node Name
kA
Phase Angle
0.0 Degrees
Source Type
SOURCE_N
Second Node Name
60.0 Hz
Source Frequency
WinIGS - Form: IGS_M112 - Copyright © A. P. Meliopoulos 1998-2013
Cancel
Isolated Grounding System ExampleExample Grounding System
Study Case :Grounding System :
Upper Layer Resistivity
400.00
(feet)
h 1Lower Layer Resistivity
400.00
Upper Layer Height (h)
40.00
(Ohm-meters)
(Ohm-meters)2
Accept
Air
2-Layer Soil Model
Program WinIGS - Form SOIL_TWOLAYER
Ground System Resistance Report Close
Study Case Title:Grounding System:
MAIN-GND GRSYS_N 2.4795 7884.82 3180.00
Rp = 2.4795 Earth Current: 3180.00Fault Current: 0.00Split Factor: N/A
Isolated Grounding System ExampleExample Grounding System
Node Name(Ohms)
Voltage CurrentResistance*(Volts) (Amperes)
Group Name
Driving Point
Equivalent Circuit Shunt Branch* Resistance Definition:
View Full Matrix
View Equivalent Ckt
Program WinIGS - Form GRD_RP01
Computer Software CalculationsClose
Native Soil
2500
Layer Resistivity
0.1000
Layer Thickness (m)
IEEE Std80 (1986)
Ref 1 (see Help)
Standard
Update
k Factor
Reduction Factor
0.7406
-0.7241
Reduction Factor - IEEE Std80 (2000 Edition)
400.0
IEEE Std80 (2000)
Upper Layer Resistivity
WinIGS - Form: GRD_RP02 - Copyright © A. P. Meliopoulos 1998-2013
IEEE Std80 (2000)
Close
0.5
IEC
Electric Shock Duration :
Permissible Body Current :
seconds
Amperes
5 % 50 %
0.14 % 5 %0.5 %
70 kg 50 kg
View Plot
( Probability of Ventricular Fibrillation : 0.5% )
Probability of Ventricular
Body Resistance :
Fibrillation :
Body Weight :
Safety Criteria - IEEE Std80 (2000 Edition)
0.222
95 %
1.0000Decrement FactorFaulted Bus
Fault Type 0.0000X/R Ratio
DC Offset Effect
N/A
N/A
Permissible Touch Voltage
Hand To Hand (Metal to Metal)
Over Native Soil
Over Insulating Surface Layer
222.0 V
355.3 V
400.0 Ohm - m
838.7 V
400.0 Ohm - m
2500.0 Ohm - m
Permissible Step Voltage
Over Native Soil
Over Insulating Surface Layer
754.9 V
2688.6 V
0.100 m
Select
WinIGS - Form: GRD_RP03 - Copyright © A. P. Meliopoulos 1998-2013
Computer Software Calculations
Computer Software Calculations
Comparison of Design Results
Manual
E touchperm = 838 V
E touchdesign= 747 V
E stepperm = 2,687 V
E stepdesignma x= 549 V
Software
E touchperm = 839 V
E touchdesign= 669 V
E stepperm = 2,689 V
E stepdesignma x= 755 V
E stepdesign = 67 V
The values listed above assume insulated layer of gravel
Grounding System Components
51
• Mechanical (compression, bolted, wedge)– Rely on surface contact and physical
pressure to maintain connection
• Exothermic – Molecular bond
Connectors
Comparison: Mechanical vs. Exothermic Connectors
Molecular bonds guarantee uniform conductivity across the entire cross section of the conductor.
Mechanical ConnectionMolecular Bond
Apparent Contact Surface Actual Contact Surface
Connectors
2000 Edition
Exothermic Connections - Rated the same as the conductor - 1083 C
Brazed Connections - 450 C based on copper based brazing alloys melting at 600 C
Pressure Connectors - 250-350 C
Bolted Connectors - 250 C
2000 Edition
Connectors meet IEEE 837, IEEE Standard for Qualifying Permanent Connections Used in Substation Grounding
National Electrical Grounding Research Project (NEGRP)
• 18 different types of buried grounding electrodes
• Layout and electrode selection was similar for each site to facilitate direct comparison of data
• Measurements were originally taken bi-monthly
• See report for complete summary
55
Mechanical vs. Exothermic
Mechanical ExothermicCompression
56
NEGRP Study - After 10 Years in the Same Soil Conditions
Compression
Mechanical Mechanical
Exothermic
57
•Exothermic - heat producing reaction
Cu Oxide + AL -> Copper + Al Oxide
Reaction Temperature at 4500° F
•Copper to numerous other metals
Steels; Stainless; Cast, Ductile, & Wrought Iron; Brass; Bronze
Provides Maintenance Free Molecular Bond
58
Exothermic Process
59
Exothermic Welding Reaction
60
Typical Substation ConnectionExothermic Welds in Grounding
Applications
61
Connector “A”, #2CYCLE #4
Connector “B”, Type “L”, #1CYCLE #8
Connector “B”, Type “C”, #1 CYCLE #10
CADWELD® TAC2V2V, #2 CYCLE #57
62
Advantages of Exothermic Connections
• Provides a molecular bond between conductors– Ensures equal current sharing between
conductor strands• Current carrying capacity equal to or
exceeding conductor ampacity• Permanent
– Will not loosen or corrode or increase in resistance
– Will last longer than conductors
IEEE Std 837 - 2002
• Four Tests – Classified As
Mechanical or Sequential.
• Four Samples of Each Connector Must Pass Each Test to Qualify
Tests for Above Grade andBelow Grade Connectors
Tensile TestsElectromagneticForce Withstand
Test
Pass if ConnectorResistance Increaseis No Greater than
50% and There is NoVisible Movement
Pass if Test Valuesare Greater ThanMinimum Pulloutand There is No
Visible Movement
Sequential TestsFor Below Grade
Connections
CurrentTemperature
Cycling
Freeze-Thaw
Acid
Pass if Connector Resistance Does NotIncrease 150% Over Intial Measurement
Sequential TestsFor Above Grade
Connections
CurrentTemperature
Cycling
Freeze-Thaw
Salt-Fog
Mechanical Tests Sequential Tests
IEEE is a registered trademark of The Institute of Electrical and Electronics Engineers, Inc.
IEEE Std. 837 - 2002• Mechanical Tests
– Test 1 - Mechanical Pullout: • The Connector Pullout Values Shall Meet Minimum Pullout Values With
No Visible Movement of the Pre-marked Conductor With Respect to the Connector
– Conductors Can Not Move Under Load of 2225 N for Sizes up to 4/0 AWG
• Mechanical Tests– Test 2 - Electromagnetic Force Withstand:
• (3) Surges, 0.2 Second Each • The Connection Shall Remain Intact With No Visible Movement of the
Pre-marked Conductor With Respect to the Connector• The Resistance of the Connection Shall Not Increase by More Than 50%.
IEEE is a registered trademark of The Institute of Electrical and Electronics Engineers, Inc.
IEEE Std 837 - 2002• Sequential Tests 3 and 4
– Current-thermal Cycling • 25 Cycles at 350° C
– Freeze-thaw • 10 Cycles; -10° to +20° C for 2 Hours
– Nitric (Acidic) and Salt Spray (Alkaline)• Nitric - 10% HNO3 Solution (Volume)• CU - Reduce Control Conductor Cross Sectional Area 80% of
Original – Salt Spray (Per ANSI/ASTM B117-85)– Fault Current (3 Surges)
• 90% Symmetrical RMS Fusing Current for 10 Seconds
IEEE is a registered trademark of The Institute of Electrical and Electronics Engineers, Inc.
IEEE Std 837 - Future
• Likely to be issued in 2014• Changes to include
• New wave forms and current levels for EMF testing• Removal of resistance criteria• Connections must be qualified for various conductor
types in order to meet IEEE 837 requirements (i.e., connector manufacturers that claim compliance with CCSC must test with CCSC)
• Above grade conductors can not be restrained
IEEE is a registered trademark of The Institute of Electrical and Electronics Engineers, Inc.
Ground Electrodes
Features & Service Life
69
Ground Rod Choices
• Solid copper rods– Expensive and difficult to drive due to softness of material
• Stainless steel rods– Option for use in soils that are corrosive to copper– Cost prohibitive in most cases
• Copper-bonded steel• Galvanized steel
70
Comparing Copper-bonded & Galvanized Steel Ground Rods
• Both rod types are composed of a steel core– Copper-bonded rods use cold drawn steel with a
tensile strength of 90,000+ psi– Most galvanized steel rods use hot rolled steel
with a tensile strength of 58,000+ psi• Higher tensile strength leads to less rod end
deformation during installation
71
Comparing Copper-bonded & Galvanized Steel Ground Rods
• The thickness and type of coating material determines corrosion resistance and service life
• Copper-bonded steel rods– Coated with 10 mils (.010” or .254mm) of
copper• Galvanized steel rods
– Coated with 3.9 mils (.0039” or .099mm) of zinc– Limited by hot dip galvanizing process
• Thicker coating = longer service life
72
• Copper is resistant to corrosion in most soils
• Zinc is sacrificial in most soils and with respect to most metals
• Corrosion protection mechanisms are different– The copper coating is designed to prevent
corrosion of the steel core– The zinc coating will delay corrosion of the
steel core by providing a sacrificial barrier
Corrosion Protective Mechanism
73
NEGRP Corrosion Protective Mechanism
Galvanized Ground Rod
Copper Bonded Steel Ground Rod
• Electrodes removed for corrosion analysis– Balboa: January 29, 2001 (9 years)– Pawnee: March 17, 2003 (11 years)– Pecos: April 12, 2004 (12 years)– Lone Mountain: April 14, 2004 (12 years)
• Moderate to severe corrosion of galvanized rods
• Minimal corrosion of copper-bonded rods• Observations were same at all sites
National Electrical Grounding Research Project (NEGRP)
NEGRP: Electrodes H & I
5/8” x 8’ Cu bonded rod 11 years exposure
¾” x 10’ galvanized rod 11 years exposure
Microscopy Evaluation
Average Cu plating loss on electrodes “E” and “G” over a 10 year period was 0.0018”
Ground Enhancement
78
Ground Enhancement - Chemical Ground Rods
79
Ground Enhancement - Bentonite
Bentonite clay• Low initial cost• Ineffective when dry • Resistivity of 2.5 Ω·m at 300% moisture• Low resistivity results mainly from an electrolytic
process• May shrink and pull away from rod or soil when it dries• IEEE® Std 80 – 2000 Section 14.5
o “It may not function well in a very dry environment, because it may shrink away from the electrode, increasing the electrode resistance”
IEEE is a registered trademark of The Institute of Electrical and Electronics Engineers, Inc.
Ground Enhancement Material (GEM)
Parameters:•Environmentally friendly •Hygroscopic•Permanent, maintenance free •Low resistivity •Unremarkable affect by wet, dry or freezing conditions•Works in any type of soil•Cost effective
81
GEM Encased Electrode (NEGRP “E”)
82
8 Years Data from NEGRP - Performance Evaluation of GEM Encased Electrodes
0
20
40
60
80
100
08/22/92 08/22/94 08/21/96 08/21/98 08/20/00
Vert. - drivenVert. - GEMHoriz. - concreteHoriz. - GEM
Mea
sure
d re
sist
ance
()
0
100
200
300
400
08/22/92 08/22/94 08/21/96 08/21/98 08/20/00
Soil resistivity, R (m)Soil moisture, M (%)Soil temperature, T (C)
T,
M a
nd R
Balboa, NEVADA
83
NEGRP Study Investigation Results of GEM Encased Electrodes
• For all investigated electrodes the resistance of GEM encased electrodes is on the average 50% lower than resistance of driven ground rods
• GEM also reduces the seasonal and long-term variability of the resistance
GEM in Grounding Wells
• Most effective way to enhance substation grounding.
• Calculate the amount of GEM required to fill the hole size.
• Place the ground rod in the hole.
• Pump down GEM by a tube from bottom of the hole up.
• Fill GEM to the top.• Holes deeper than 10 feet
should use pump
GEM
Water
Rock
NCC
Conductors
Copper Theft
• US Department of Energy estimates over US $1 Billion in copper theft annually
From Surveillance Video of Actual Theft
Copper Theft
Even birds are stealing copper…
Methods for Copper Theft Prevention
• Painting• Signage• Alternative Coatings• Encoding / Marking • Covering (PVC Conduit,
etc.)• CCTV Systems• Motion Detectors /
lighting• Alternative Materials• Theft Monitoring systems
89
• Material– Copper– Copper - bonded steel– Copper – clad steel– Composite
• Size– Sufficient to withstand maximum fault current for maximum
clearing time– Resist underground corrosion
Conductors
90
Advantages of Copper Conductors
• Copper is the most common material used for grounding
• Copper has high conductivity• Copper is resistant to most underground
corrosions• Copper is cathodic with respect to most
other metals that can be buried in it’s vicinity
91
Advantages of Copper-Clad Steel & Copper-Bonded Steel Conductors
• Combines the strength of steel with the corrosion resistance of copper
• It is more economical• It is more resistant to damage and theft • Low scrap value adds to theft deterrence
Formed Copper-bonded Steel
Conductors
93
UL® 467 30o Bend Test
UL is a registered trademark of UL LLC.
94
UL® 467 30o Bend TestGalvanized Steel
Conductors
Copper Jacketed Steel ConductorCopper Bonded Steel Conductor
95
Field-bent Copper-bonded Conductor
Substation ground leads
96
Pre-bent Copper-bonded Conductor
Composite Conductors
Composite Conductor Chart
ERICO Confidential 99
Composite Conductor Testing
Composite Conductor Features
• Copper strands are hidden by outer tin plated copper bonded steel strands
• Copper strands are tinned for superior corrosion resistance
• The copper stranding increases conductivity and flexibility of the conductor
• Comes in bare or insulated option• Available in five configurations
Composite Conductor Advantages
• Has many years of proven record in successful field applications in all major rail companies in the USA
• Combines conductivity of copper with strength of steel
• Difficult to cut with hand tools• The outer steel strands are magnetic which
further deters thieves looking for copper.
Composite Cable Applications
Thank you for your time!
This concludes the educational content of this activity
www.erico.com