Grounding Tutorial

Substation Ground System Design & Standard IEEE 80

Terry Klimchack

Revised 03/10/14

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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

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