Temperature and Grid Control Density Simulation in Overhead Ground Wire Cable with Fiber Cable (OPGW) under Short Circuit Current Passage

The MAIN JOURNAL for POWER GRID SPECIALISTS in RUSSIA

30

August 25–29, France, Paris

Grid Control

A

long with the standard information 

fi

 ber-

optic cables (FOC), made with dielectric self 
supporting cables, overhead ground-wire 
cables made of steel wires with different 

coatings containing stainless steel module which 
comprises optical 

fi

 bers in hydrophobic semi-liquid gel 

are widely used (OPGW). This design provides necessary 
mechanical strength and is a product of dual purpose: it 
performs the traditional role of protecting power lines 
from lightning strikes and used as communication and 
data transfer cable.

OPGW must satisfy JSC FGC UES traditional 

requirements to overhead ground-wire cables: mechanical 
strength, corrosion resistance, resistance to lightning 
discharges, Aeolian vibrations, Galloping, as well as short 
circuit withstand capability.

Steel wire used in OPGW layers must be protected 

against corrosion, therefore zinc or aluminum coatings, 
signi

fi

 cantly more resistant to oxidation than steel core, 

are used. Resistance to corrosion and speci

fi

 c conductivity 

of aluminum coating is slightly higher than zinc, however, 
such coatings have a number of disadvantages. Outdoor 
contact of stainless steel and aluminum causes active 
corrosion: atmospheric salt and chemical contaminations 
on the surface of the metal act as the electrolyte and lead 
to accelerated destruction of aluminum. Therefore the 
international standard IEEE-1138-2009 for zones with 
high corrosive activity, which include all industrial and 

Temperature and Current 

Density Simulation in Overhead 

GroundWire Cable with Fiber 

Cable (OPGW) under Short

Circuit Current Passage

Leonid GUREVICH (

Леонид

ГУРЕВИЧ

),

 Vladimir DANENKO (

Владимир

ДАНЕНКО

),

 Dmitry Pronichev (

Дмитрий

ПРОНИЧЕВ

),

М

ikhail TRUNOV (M

ихаил

ТРУНОВ

), 

Volgograd State Technical University

31

[email protected],   www.eepr.ru

densely populated areas, prohibits the usage of OPGW 
optical module made of stainless steel and aluminum 
coated wires.

Moreover, the comparative tests to withstand lightning 

charge up to 110 coulomb carried out on “Four-part 
lightning current generator” (GTM-4) test bench in 
Moscow Power Engineering Institute under the same 
tension revealed that shield wire made of aluminum-clad 
steel wire suffered the greatest damage.

OPGW usage requires to calculate thermal resistance, 

provided that not only residual mechanical strength of 
the cable, but also effective heat removal from the optical 
module are considered. Regulations for design of 

fi

 ber-

optic communication lines on OHL 
require thermal stability analysis of 
optical cable when subjected to fault 
currents.

OPGW thermal withstand analysis 

included the following calculations: 
• dynamic magnetic 

fi

 eld  caused 

by the AC pulse frequency of 50 
Hz and a duration of up to 1 s in 
order to obtain the current density 
distribution in each of the cable 
conductors, depending on the time;

• unsteady temperature 

fi

 eld  using 

Joule losses as the heat source.
The simulation used Magnetic 

Fields and Heat Transfer in Solids 
modules license software package 
COMSOL Multiphysics, capable of 
solving partial differential equations.

For simulation diagram of ground 

wire with grade OPGW 11,0/

Е

1(12)-

MZ (ground wire with diameter 
11.0 mm with built-in optical 

Fig. 1. OPGW thermal withstand capability 

design diagram: 1 — air; 2 — steel wire; 

3 — central tube; 4 — optical 

fi

 bers in 

hydrophobic gel; 5 — the line along which data is 

presented in Fig. 2. 

Fig. 2. Temperature distribution in OPGW along the line shown in 

Fig. 1 at 

J

fc

 = 4.3 kA current through 1 s: 

1 — uncoated steel wires, 2 — zinc coating, 3 and 4 — aluminum 

coating, thickness 20 and 260 

μ

m

communication cable) made according to the technical 
conditions enterprise standard 71915393-TU 113-2013 
(Fig. 1) was used. 

While thermal analysis four possible variants of steel 

wire surface coating were compared:
•  steel rods with zinc coating for particularly harsh 

environment operation (corresponds to OPGW really 
made by Severstal-Metiz JAC according to enterprise 
standard 71915393-TU 113-2013);

•  steel rods without coating;
•  steel rods with aluminium coating which thickness 

corresponds to zin

с

 coating of 

fi

 rst variant (20 

μ

m);

•  steel rods with aluminium coating with volume 

aluminium content up to 25%.
The simulation results were veri

fi

 ed by experimental 

data of 

fi

 eld tests in OPGW high voltage equipment test 

center of JSC NTC FGC UES showing that 1 second 
passage of 4.3 kA short circuit current increased cable 
temperature by an average of 88°C. 

It was found that current density in uncoated steel wire 

increases with distance from the axis of the cable, which 
leads to substantial increase in temperature in the outer 
wire layers (Fig. 2).

The use of zinc or aluminum coating results in 

predominant current 

fl

 ow in them (current density in these 

coatings respectively is 4 and 9 times the current density 
in the carbon steel core). The difference in current density 
in external and internal layers is not signi

fi

 cant. Under 1 

second fault current 

J

fc

 = 4.3 kA the use of coating zinc 

reduced the temperature in optical module area by 35° 
C and in the outer layer — by 83° C. The use of 20 

μ

m 

aluminum coating with increased electrical conductivity 
allows to further reduce the temperature in the optical 

32

August 25–29, France, Paris

Grid Control

module by 15° C, however, in the case of both zinc and 
aluminum coatings temperatures lie in the safe range and 
do not lead to degradation of optical properties of optical 

fi

 ber. During simulation the increase of aluminum coating 

thicknesses to 25% volumetric content provided under 
selected current value of 

J

fc

 = 4.3 kA temperature increase 

only up to 52°C. This aluminum content is too high with 
respect to temperature stability at current 

J

fc

 = 4.3 kA and 

is appropriate only at 

J

fc

 = 6.2—6.3 kA currents.

Speci

fi

 c resistance/cable coating dependence is often 

not analyzed in choosing OPGW wire coating material. 
For OPGW under consideration when using uncoated 
steel wires DC resistance value 

R

 = 3.1 ohm/km, with 

zinc coating 

R

 = 2.2 ohm/km, with 20 

μ

m thick aluminum 

coating 

R

 = 1.9 ohm/km.

Shield wire DC resistance reduction when replacing zinc 

coating for aluminum will inevitably lead to an increase 

in forced and active components of fault current that can 
neutralize determined by laboratory testing and modeling 
the lower values of temperature 

fi

 elds in ground steel wires 

with aluminum coating over wires with zinc coating.

Change in strength characteristics and critical de

fl

 ection 

for OPGW made by Volgograd Af

fi

 liate of Severstal-

Metiz when replacing steel galvanized rod of 1770 MPa 
marking group with steel aluminized one with aluminium 
volume content 25% was evaluated. Cross-sectional area 
of all wires in OPGW of existing construction is 83.59 
mm

2

, approximate weight of 1000 m lubricated ground 

cable is 695 kg and actual aggregate breaking strength is 
at least 147 kN. OPGW coating changed, the weight is 
reduced to 515 kg. Aluminum-coated steel wire tensile 
strength 

σ

bim

 calculated according to the additivity concept 

is 1342 MPa and actual aggregate breaking strength of all 
wires is less than 112 kN. 

Table 1. Calculation of linear and speci

fi

 c loads in OPGW under its own weight, the weight 

of ice and wind pressure 

Load Designation

OPGW with Galvanized Rods

OPGW with Aluminized Rods

Linear Load, N/m

Speci

fi

 c Load, MPa/m

Linear Load, 

N/m

Speci

fi

 c Load, 

MPa/m

from proper weight

6.82

0.0815

5.05

0.0604

from glaze ice weight

19.11

—

19.11

—

from wind pressure while glaze ice

24.72

—

24.72

—

resultant from proper weight, glaze ice 

weight and wind pressure while glaze ice

40.22

0.6415

39.11

0.6238

33

[email protected],   www.eepr.ru

When using OPGW in Russian area of the third groups 

by wind pressure (1 time per 25 years wind pressure up to 
0.67 kPa) and by glaze ice (1 time per 25 years standard 
thickness of glaze ice layer up to 20 mm) calculation 
according to EIC-7 results in the following values of 
linear and speci

fi

 c loads (Table 1).

With a span length of 

l

=300 m minimum allowable 

sag under the action of wind and ice loads at permissible 
stresses in ground wire equal to 50% of ultimate tensile 
strength of the wire being used is 8.15 m for OPGW 
of galvanized steel wires and 10.46 m for OPGW of 
aluminum-coated steel wire.

Thus, the use of aluminized wire with high aluminium 

content in OPGW manufacture leads to considerable 
reduce in bearing capacity of the cable not compensated 
by the decrease of mass per unit length.

CONCLUSIONS

1. A method for modeling the distribution of current 

density and temperature over OPGW cross-section 
manufactured by the TU STO 71915393-

Т

U 113-2013 

and veri

fi

 ed by the results of environmental tests in HV 

EC of JSC FGC UES was developed.

2. Use of galvanized steel wire in the plastically 

deformed OPGW outer layer under 1-second 4.3 kA max 
fault current passage allowed to reduce the temperature on 
the surface of the optical module by 35°

С

 compared with 

an uncoated steel wire rope.

Aluminum coating allows to make additional 

reduction of temperature but its use is associated 
with a number of negative factors: the low corrosion 
resistance of aluminium coating in the contact area with 
the optical module stainless tube; low lightning strike 
withstandability of aluminum wire.

When it comes to choosing which 

type of protective coating to use for steel 
wires it should be taken into account not 
only the possible change of temperature 

fi

 elds in OPGW under the same values 

of fault current, but also dependence 
of its size on speci

fi

 c resistivity of the 

shield wire, as well as lightning current 
withstandability, corrosion resistance 
and carrying capacity of the shield wire.

REFERENCES

1. Tro

fi

mov B.L., Features when 

choosing optical cable for overhead 
transmission lines / B. L. Tro

fi

 mov, D. 

M. Indebaum // Power engineering 
and industry of Russia, 2012, No 12, 
(200). P. 29.

2. 

Study of lightning strike and 
mechanical impact withstandability 
of shield wires / A.K. Vlasov, V.A. 
Fokin, V.F. Danenko, V.I. Frolov, 
E.Yu. Kuskina // Steel. — 2003, No 9, 

P. 66—70. 

3.  Mekhanoshin B. I. An integrated approach to ensure 

OHL lighting-surge proofness / B.I. Mekhanoshin, 
O.I. Bogdanova, M.Z. Ghiliazov, D.A. Matveev. — 
Transactions of the Russian III Conference on Lightning 
protection. St. Petersburg, May 22—23, 2012, http://
lightningprotection.ru/wp-content/uploads/ — 22—
23 May 2012. Pdf.

4. Rules of Designing, Construction and Operation 

of Fiber Optic Communication Line in Overhead 
Transmission Lines with Voltage 110 kV and Higher. 
M.: RAO UES of Russia, 1999. 108 p.

5. Vlasov A.K., On strengthening service properties 

of shield wires for lightning protection of overhead 
electrical power lines / A.K. Vlasov, V.A. Fokin, V.V. 
Petrovich, V.I. Frolov, V.F. Danenko // Steel. 2011, 
No 7, p. 78—81. 

6. Pat. 2441293 C1 RF, IPC H01 11/22. Shield wire 

with 

fi

 ber-optical communication cable. / Vlasov 

A.K., Fokin V.A., Petrovich V.V., Frolov V.I. applied 
03.11.2010, publ. 27.01.2012. Bul. No 3. 

7. STO 71915393-

ТУ

 113-2013. Severstal-Metiz. Steel 

ropes (ground wire) to protect the overhead power lines 
from direct lightning strikes. Technical conditions. 
Volgograd. 2008. 

8. STO 56947007-29.060.50.122-2012 JSC FGC UES 

Guidance on calculation of melting ice on overhead 
ground-wire cable with integrated optical cable 
(OPGW) and application of the distributed temperature 
control in OPGW melting. Effective date: 05.18.2012, 
JSC FGC UES2012, p. 119.

9. Methodological guidelines for calculating thermal 

stability of OHL shield wires. M. Energosetproekt. 
1976.