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Low-Frictional, Abrasion-Resistant Optical Drop Cable with
Rectangular Strength Member

1.

2.

INTRODUCTION

Recently, fiber to the home (FTTH) subscribers are
increasing, not only in homes but also in multi-dwelling
unit (MDU). In MDU, optical fiber is wired to an ONU(Optical Network Unit), its installation method consists ofpassing it through an abrasion-resistant-low frictional optical drop cable within a wiring conduit line. (Figure 1)
A special plastic, with superior abrasion-resistivity andlow-frictional properties, is applied to the optical dropcable as a sheath material. This sheath decreases the frictional resistance and the abrasion damages on the optical
drop cable coating, which are caused by its contact withthe existing cables and inner surface of the wiring conduit
line. Usually, these special plastics are high in strengthand rigidity, therefore cables sheathed with these special
plastics are hard to be bent. Then, these cables havebending problems when storing in rosettes or cabinets.
Now, we designed a new rectangular (tape-shaped)
strength member, which bends easily and has mechanicalstrength equal to traditional strength members. By using
this strength member, a low-frictional abrasion-resistant
optical cable is developed and solves the problem.
MDUClosure

FEATURES

2.1 RECTANGULAR STREBGTH MEMBER
Comparison of features of traditional strength member
and newly developed rectangular strength member isshown in Table 1. Comparisons of appearance and ofconstruction are shown in Figure 2 and 3.
Table 1Comparison of features of strength members.
Rectangularstrength member

Traditionalstrength member

FRP dimension (mm)0.75×0.26

φ0.5

Aramid fiber amount(relative value)1(Same as traditional one)

1ItemsRupture strength (N)

300

300

Modulus of elongation (MPa)49,00049,000

Repulsion at 15 mm radius(Bending rigidity, relativevalue)

0.77

1

While thickness, in bending radius direction, of traditional strength member is 0.5 mm, that of the newly developed rectangular strength member is as small as
0.26 mm. With this construction, the bending rigidity canbe decreased. The strength member is composed of thesame materials as the traditional strength member.

Optical drop cable
Optical ﬁber

Strength member

Conduit linea）Rectangular strength member. b）Traditional strength member.

Figure 1

Optical drop cable installation.
Figure 2

Appearance of strength member.
Aramid ﬁber

0.75 mm
Adhesion layer
0.26 mmAramid ﬁber

Adhesion layer
0.5 mmImpregnated resin

Impregnated resina）Construction of rectangular strength member. (Aramid ﬁber FRP)

Figure 3b）Construction of traditional strength member. (Aramid ﬁber FRP)

Structure comparison of strength member.

Furukawa Review, No. 37

20101

Low-Frictional, Abrasion-Resistant Optical Drop Cable with Rectangular Strength Member

2.2 EASE OF CABLE BENDING
Repulsive force (bending rigidity) measurement on cableportion of both optical drop cables, in which traditional
strength member and rectangular strength member areused, is performed. Test method is shown in Figure 4 andtest result is shown in Figure 5. At every bending radius
the cable portion with rectangular strength member
shows 20 to 25 % lower value than that of the traditional
cable.
Cable sample

The cable portion of the low-frictional abrasion-resistant
optical drop cable, with rectangular strength member,accommodated in optical rosette is shown in Figure 6. In
a rosette, a cable shall be bent in small radius. The developed cable can be easily accommodated because of its
superior flexibility.
RosetteトMovable plate

Bending radius

Indoor cable̲ ̲ ̲ gFigure 6
Load measurement at speciﬁed bending radius

Test method of bending rigidity.

300

Repulsive force at bent
(Bending rigidity)(gf)250

Connector

Movable plate
positionadjusting dial

Electronicbalance

Figure 4

Cable portion of optical drop cable

Rectangular strength member
Traditional strength member

200

Accommodation in optical rosette.

2.3 LINE-UP
Constructions of low-frictional and abrasion-resistant optical drop cable (1, 2, 4, and 8 cores types) are shown in
Figure 7, and characteristics are shown in Table 2. The
outer shape and dimension of the developed cable are
the same as those of the traditional optical drop cable,
and the developed cable can be installed in traditional
peripheral connecting parts.
Furthermore, single mode type optical fiber (FlexiWave), which can be bent in 15 mm radius, is used.

150100500301510Bending radius (mm)Figure 5

Test result of bending rigidity.

Rectangular strength member
Rectangular strength member
Rectangular strength member
Rectangular strength member
Abrasion resistant FlexiWave ﬁber
Abrasion resistant FlexiWave ﬁber
Abrasion resistantFlexiWave ﬁber
low frictional
low frictional（4C ribbon ﬁber） low frictional(2C×4C（2C）
sheath material
sheath material
sheath material
ribbon ﬁber)
Steel wire
Steel wire
Steel wire
Steel wire

FlexiWave ﬁber
（1C）

Abrasion resistant low frictional
sheath material
Standard dimension：
2.0 mm × 5.3 mma）1C cable.

Standard dimension：
2.0 mm × 5.3 mmb）2C cable.

Figure 6

Standard dimension：
2.0 mm × 5.9 mmd）8C cable.

Standard dimension：
2.0 mm × 5.9 mmc）4C cable.

Structures of optical drop cable with rectangular strength member.

Furukawa Review, No. 37

2010

2

Low-Frictional, Abrasion-Resistant Optical Drop Cable with Rectangular Strength Member

Table 2
Test item

Cable characteristics.

Test condition

1 core2 cores

4 cores

8 cores

Transmission loss

Test wave length λ= 1310 nm
Test wave length λ= 1550 nm< 0.35 dB/km< 0.21 dB/km< 0.35 dB/km< 0.21 dB/km< 0.34 dB/km< 0.21 dB/km< 0.35 dB/km< 0.22 dB/km

Tension1000 N< 0.1 dB

< 0.1 dB

< 0.1 dB

< 0.1 dB

< 0.1 dB

< 0.1 dB

< 0.1 dB

< 0.1 dB

< 0.1 dB

< 0.1 dB

< 0.1 dB

< 0.1 dB

Bending
Lateral pressure
Impact

R=15 mm × 10 Cycles (1C · 2C)
R=30 mm × 10 Cycles (4C · 8C)
1200 N/25 mm (1C · 2C)
1960 N/100 mm (4C · 8C)
300 g × 1 m< 0.1 dB

< 0.1 dB

< 0.1 dB

< 0.1 dB

< 0.05 dB/km< 0.05 dB/km< 0.05 dB/km< 0.05 dB/km

JIS C 3005 declination

Natural extinguishing

Natural extinguishing

Natural extinguishing

Natural extinguishing

JIC C 3521 vertical tray−−

Temperature characteristics −30 ~ 70°C
Fire retardancy

Damaged length < 1.8 m Damaged length < 1.8 m

Test wave length λ=1550 nm

3.

IN CONCLUSION

Low-frictional and abrasion-resistant (1, 2, 4 and 8corestypes) optical drop cable is developed. This cable is easy
to be bent in small radius and easily installed in a rosetteand in a cabinet. Furthermore, as outside diameter andcable characteristics are same as the traditional cable,
this cable is treated in the same manner as the traditionalcable.
For more information, please contact:
Engineering Department, Telecommunications Company.
TEL: +81-3-3286-3440
FAX: +81-3-3286-3190

Furukawa Review, No. 37

20103