WCA March 2017

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Wire & Cable ASIA – March/April 2017
Investigating effects of
freezing conditions on
micro-duct air-blown
cables
By Yunfang Ruan, Zhuang Xiong, Xiaoli Liu and Wenjing Ye, State Key Laboratory of Optical Fibre and Cable Manufacture
Technology, Yangtze Optical Fibre and Cable Joint Stock Co Ltd, and Huawei Technologies Co Ltd, Shenzhen,
Guangdong, China
❍
❍ Figure 1: Micro-duct with cable soaked in water
Cable type
Stranded loose tube
structure
with G.652D fibres
Fibre count 96
Cable OD 6.1mm
Micro-duct type HDPE
OD/ID of micro-duct 10/8mm
TCT cycles 2
❍
❍ Table 1: Common test conditions
Abstract
In some cold areas, freezing conditions are a potential
threat to micro-duct air-blown cables. In order to study
the effects of freezing conditions on the transmission
performance of optical fibres in micro-duct air-blown
cables, two different experiments were designed and
carried out in this paper.
The test results reveal that both freezing in micro-ducts
and that around end caps have insignificant influence on
the transmission performance of the fibres and no visual
physical damage to the cable has been detected after the
experiments.
1 Introduction
With the development of FTTx network construction,
micro-duct air-blown cables are more frequently used due
to the lack of duct resources, even in some cold regions. In
this case, the water permeated into the micro-duct will be
frozen under such low temperatures.
Some concern such as the cable performance
deterioration will discourage the wide application of
micro-duct air-blown cables all over the world.
In order to study the effects of freezing conditions on the
transmission performance of optical fibres, freezing tests
were designed to simulate the cold climate with the aid of
a temperature cycling chamber.
During the tests, the attenuation change of the fibres was
monitored, and the appearance of the cable was checked.
The test procedures are described in detail and the test
results are carefully analysed.
2 Freezing test conditions
Two experiments were designed to simulate the conditions
of water frozen in the micro-duct and around the end caps
respectively with the aid of a temperature cycling chamber.
The common test conditions in two experiments are shown
in Table 1.
3 Test for water frozen in micro-duct
This experiment is designed to study the impact
of freezing conditions on fibre attenuation while water is
frozen in the micro-duct, and performed in accordance
with IEC60794-1-22 Method F15: cable external freezing
test.