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Wire & Cable ASIA – September/October 2007
56
Nove ber/De ember 2 11
1 Riser cable assembly
The recent emergence of single mode fibres for FTTH
applications with improved bending performance has
been driven by the increasing amount of optical cable
being installed inside buildings with all the associated
bend challenges.
As mentioned before, the speed of deployment creates
another main challenge in today’s installations and the
pre-connectorised riser solution has been specifically
designed to overcome this issue. As the FTTH scale of
deployment increases, customers will have trouble finding
enough skilled splicing technicians.
Additionally, labour rates for highly skilled fibre craftsmen
are already increasing. The proposed solution enables
considerable advantages in the speed of deployment,
while significantly decreasing the number of skilled
installers needed to complete an installation successfully.
Faster deployment time will allow customers to generate
revenue faster, thus increasing their ROI. The main element
of the proposed solution is a pre-connectorised riser cable
shown schematically in
Figure 1
.
This solution is based on bend insensitive fibre, which
makes it ideal for deployments within the challenging
MDU environment. The riser assembly provides single
connectors (SC or LC type) on the basement side to
be connected to a basement distribution terminal and
individual fibre breakouts on each floor level to be
connected to the individual customer apartments.
All connectors and the breakouts on the floor level are
factory assembled and therefore avoid the critical step of a
typical mid span access of the cable.
The cable is already 100% factory tested before being
delivered to the deployment site ie MDU. The riser
assembly is built according to the exact individual MDU
architecture.
Only very basic parameters like the distance between
floors (F) and the distance from the basement distribution
terminal to the first floor breakout point (B) have to be
provided in order to enable this (
Figure 2
).
Based on this information even installers not used to
handling fibre can deploy the proposed cable very quickly.
The basement tail length is predefined at 120cm for easy
connection into the basement distribution terminal.
The length of the individual breakout tethers at the
floor level depends on the given floor height (F) and are
predefined as F-15cm as the maximum length. In order
to minimise the cable diameter during installation the
connectors at each floor level are staggered along the
main cable during the installation procedure.
The cable assembly comes with a pulling grip for easy
installation. The extension distance from the last tap point
to the pulling grip is predefined at 5m. Different connector
types such as SC or LC can be chosen for the complete
assembly.
❍
❍
Figure 3
:
Micromodule cable (up to 144f)
OD = 7.6mm
OD = 9.0mm
❍
❍
Figure 4
:
Testing setup
Duct
Gap size
Riser
cable
Misalignment
Pulling grip
Pulling direction
Strain
gauge
Duct
❍
❍
Figure 5
:
Pulling force vs Duct fill ratio
PF Pulling force [N]
Duct fill ratio [%]