NO. TRI-TEC-002

Technical Report for ACFR® Conductor
Keywords – Stranded Carbon Fibre composite Cable, Flexibility, Ohmic loss, Easy Installation

Abstract:

Globally ACSR and AAAC conductors arecommonly used as overhead conductor forenergy delivery application. High density
transmission corridors are the need of energy
utilities to optimise the right of way. So the useof High Temperature Low Sag (HTLS)
conductors has been increased to address theincreasing congestions in the exitingtransmission network.
The selection ofsuitable HTLS technology considering therequirement with respect to increase in powertransfer capacity, existing ground clearance,
existing tower loading and cost of capital
investment is not only the deciding factor but
also the operational efficiency (Ohmic losses)
over a period of its lift time and installation of
those conductors in the existing terrain are themajor parameters needs to be considered forthe right technology adoption. We directed
our attention to this operation efficiency andeasy installation and developed and tested
Aluminium Conductor Fiber Reinforced(ACFR®) conductor and it’s Carbon Fiber
Composite Cable (CFCC®) as the core.

General:ACFR® is one of HTLS conductor and its
construction shown in Fig 1 is as simple as ACSR
conductor where the stranded steel core is
replaced with stranded carbon fiber core. Theouter conductive layer is either EC grade harddrawn aluminium wire used in ACSR conductoror thermal resistance wire of Al-Zr alloy or EC
grade thermal resistance annealed aluminium
wire. And trapezoidal wire shaped is selected
to increase conductive area which leads tobetter ohmic losses. The selection of the outerconductive layer’s material and shape depends
on application and the preference of theenergy utilities.

Fig 1: ACFR® Conductor’s product description and its construction

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CFCC® Core:
Now a day, the carbon fiber composite core
conductor technology has been preferred by theutilities among HTLS conductor technology becauseof high strength to weight ratio, lower thermal
expansion and almost zero creep. The popular
composite core technology are mostly a single coreor several number of single wires bunched together.
But the challenge of this popular carbon fibercomposite core technology is flexibility which leads
to handling and installation work. We developed atechnology to strand carbon fiber composite

materials called CFCC® core to make it flexible andeasy to handle during installation. This innovatedtechnology is coming from accumulated know-how
about stranding material like steel and fiber in otherbusiness field which is Tokyo rope’s corecompetence. CFCC® core consists mainly of carbon
fibers (filaments) and matrix resins. Table 1
compares the characteristics of CFCC® core andsteel stranded wire. CFCC® has 1/5 the weight, 1/12
the thermal expansion coefficient compared withthe same size steel wire.

ItemCharacteristcis

MaterialCFCC

SteelStrands

7/2.6

7/2.6

37.20

37.16

Calculated Cross Section

mm2

Outer Diameter

mm

2

7.8

7.8

Weight

kg/km

60.0

291.3

Tensile LoadkN

79.5

44.0

Elastic Modulus

N/mm2

126,000

206,000

Thermal Expansion

10-6/℃

1.0

11.5

Table 1: CFCC® & Steel core characteristics comparison
ACFR® Characteristics
ACFR®’s maximum operation temperature is 180℃
(Emergency 200℃). This temperature limitations
do not come from the aluminium wires but fromthe CFCC® core, as temperatures approaching thelimit or higher can accelerate aging if sustained forlong periods of time. CFCC® core is designed for
180℃ at maximum operation temperature
The comparison of conductor characteristics ofACSR 428 mm2 (Zebra type) & ACFR 520 mm2 isshown in Table 2. The aluminium cross section areaof ACFR® is higher than ACSR, making the current
carrying capacity 2 times more than ACSR bymaintain same sag. DC resistance of ACFR®
conductor is less than 20 % of the ACSR Conductor.

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Description
AL Type
AL Shape
Diameter
WeightArea
DC resistanceUTS
MCOTAmpacity
MOE Below KPT
MOE Above KPTCTE Below KPTCTE Above KPT

Unit

ACSR 428

ACFR 520-1350-H19

1350-O

mm
kg/km

Round
28.62
1621
484
0.06868
129
85
562
7190
19380
19.44
11.5

Trapezoidal
28.14
1540
570
0.0536
147
180
1617
6407
13770
18.38
1mm2
ohm/kmkN℃
A
kg/mm2kg/mm2
10-6/℃10-6/℃

Table 2: ACSR & ACFR® Characteristics (Zebra)

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ACSR & ACFR® Sag and Temperature
Characteristics:
Next is a comparison of the sag and temperature
characteristics shown in Fig. 2, when stringing witha span length of 350 m? The sag at 80°C, which isthe continuous allowable temperature of normal
type conductor ACSR, is 6.7 m for ACFR® against
9.43 m for ACSR. ACFR® can suppress sag by about
2 m. Moreover, in the case of maximum operating
temperature at 180℃ , the sag for ACFR® is about
Fig 3: ACFR®’s knee point

only 7.2 meters that which still maintains theground clearance.

Various Performance Test Results
We conducted various performance tests forconductor and core shown in table 3 in respect toDesign, Installation, and Service / operation aspectusing outside accredited laboratory and the results
were all satisfactory.
DesignFig 2: ACSR and ACFR® Sag & Temperature

Sag Tension Design
When the temperature of the conductor increased,
the aluminium wires usually expand than higher
rate than the core. This expansion is accompanied
by a proportional reduction in its share of the total
tensile load on the conductor. At a giventemperature (called the "knee-point" shown in Fig3), the aluminium becomes mechanically"unloaded", the ACFR® conductor being supported
only by its core. It is at this point that the sag isgoverned only by the thermal expansion of the core.
Knee point temperature is around 50 to 80℃ incase of annealed wire type.

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Installation

Service/Operation

Tensile Strength
SheaveStress Strain
Bending
Electric Resistance Torsion
Creep
Radial Crush
Thermal Expansion
Tg
Flexural Strength
Elongation

Sag / Tension
Salt SprayHeat Exposure
Heat Stress
Temperature Cycle
Strand Brittle Fracture
UV aging

Table 3: List of ACFR®’s implemented Tests

Some of the testing result are described here.
Heat Exposure (for CFCC® core):
Maximum operation temperature for ACFR® is180 ℃. This temperature limit is determined by thethermal endurance capability of the CFCC® core. In
order to check its capability, CFCC® core wasexposed to 180 ℃ and each three ( 3 ) samples at
400-hour, 1500-hour, 2500-hour, 5000-hour, 52
weeks were measured their remaining tensile
strength. Its result from each set were ten plottedon a log-log Chart and its residual strength wasextrapolated out to forty (40) years. Calculated
strength after 40 years was 106.1% RTS shown in Fig
4.

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NO. TRI-TEC-002

Corrosion Resistance (for ACFR® conductor):
Corrosion of the inner layer aluminium wires
contacting the composite cable pose a problem. We
examined the corrosion resistance of ACFR® basedon CIGRE TB 426 which recommend to do salt spraytest. Test was performed according to ASTM
B117 for 1,000 hours. Result was that there wereno significant degradation about tensile strength ofaluminium and core, Tg, and flexural strength
shown in Fig5 and 6.
Fig 4: Heat exposure Test at Kinectrics

Heat Stress (for CFCC® core):
Emergency operating temperature for ACFR® is200 ℃. This temperature limit also determined by
the thermal endurance capability of the CFCC® core.
CFCC® core was exposed to 200 ℃ and tensioned at
25% RTS for 1000 hours shown in Pic 1. Its test
result was more than 95% RTS.

Pic 1: Core installed for heat stress at Kinectrics

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Fig 5: Measured tensile strength of AluminiumFig 6: Result of Salt Spray Test at Kinectrics

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Fittings & Accessories
ACFR® conductor is installed using conventional
tools and equipment. While the installation ofACFR® Dead ends and splices is slightly different
from the conventional conductor’s fittings, but theconductors are installed with similar way.

conductor which may lead to conductor’s snapping.
We usually dispatch our stringing advisor for lectureand monitoring in addition to providing stringing
guideline as shown in Fig 7.

Tension Joint
Design of dead end clamp for ACFR® is similar withthat of ACSR except for using aluminium buffer inorder to reduce the suppressing and crushing force
to CFCC® core. The sleeve was slightly longer at fulllength than the sleeve for ACSR, which leads to fully
secured endurance at high temperature as well as
grip strength. An example of the compression typedead-end clamp and mid span joint for ACFR® isshown in Pic 2 and 3.

Fig 7 : Installation Guide LinePic: 2 Dead end clamp of ACFR®

Pic 3: Mid Span of ACFR®

InstallationThe ACFR® conductor’s stringing method is quite
similar with conventional ACSR’s one thanks to its
flexibility. This is the one of the biggest advantageof ACFR® which use stranded CFCC® core.
Difference are only two point which are needs ofextra caution about twisting and over-bending of

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History and Operation Record
The research and development to strand thecarbon fiber composite material to make it more
flexible started in the year 1980’s. The CFCC® core
was first tested for civil construction application
mainly focusing to replace the steel reinforcementwith CFCC® to enhance corrosion resistance. The
first deployment of CFCC® core for civil construction
application was PC bridge project in Japan in theyear 1986. In the year 2002 the CFCC® core wasused instead of steel core in the overhead
conductor application, the new conductor withcarbon fiber composite core named ACFR® wasintroduced, tested and deployed in one of thetransmission line project in Japan shown in Pic 4.
This is the world first overhead transmission line
using carbon fiber composite core and hadenergized in satisfactory operation until 2019. Afterchecking product validity which took more than 10years, we have started to promote our technology
all over the world since 2012. Now ACFR® are usedin Japan, China, Indonesia, India, Brazil and USA etc.

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NO. TRI-TEC-002

2) Long spans for new line

Pic 4: 66KV ACFR® line in Japan
Case Study

HTLS conductors have been utilized for not only
upgrading existing lines but also for allowing longer
spans for newly constructed lines while maintaining
required clearance and capacity. TACFR (Thermoresistant Aluminum-alloy Conductor FiberReinforced) in the table5 was used for the newconstruction of 132kV line (3 phase x 1 circuit) in
steep mountainous terrain in Brazil. TACFR wasused for relatively longer spans in the mountainous
terrain which contains over 1000m long spans dueto the cancellation of some towers (ROW problems)
while conventional ACSR Linnet was installed formoderate spans in the flat terrain. In this area,
sharp mountain faces and hilly terrain result in alimited number of ‘feasible’ tension/pull sites sothat conductor was installed by Lay out method.
Reduction in the number of towers can lead to
reduction of initial construction cost.

1) Amps upgrade by re-conducting
Here is the 132KV re-conducting ampacity upgrade
project case study among well-known HTLS
conductors shown in table 4. Utility expect 1000
amps from the current 379amps (more than 2.5times) keeping ground clearance. ACFR®
conductors shown in table 4. Utility expect 1000
Amps from current 379 Amps (more than 2.5 times)
keeping ground clearance. ACFR® conductor canachieve the required 1000 Amps with the best
ohmic losses keeping the same sag as existing ACSR.

Table 5: Comparison ACSR vs TACFR

Pic 5: 1087m long span (300m elevation difference)

Conclusion

Table 4: Case study for 132kV

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ACFR® conductor which use stranded CFCC® corehas outstanding advantages including lesser AC
resistance and easy installation. ACFR® conductor
technology will contribute to energy industry inyour country.

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NO. TRI-TEC-002

Contact Information
Questions regarding this report may be submitted to the Tokyo Rope International contacts listed below.
Questions will be answered by e‐mail in a timely manner.

Ryuta ( Luke ) Ogoshi
International Marketingogoshi.ryuta@tokyorope.jp

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Masaki Takayama
International Marketingtakayama.masaki@tokyorope.jp

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