WCA March 2017

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74 Wire & Cable ASIA – March/April 2017
A 1.8km-long micro-duct air-blown cable and 80m-long
micro-duct are used in this experiment.
3.1 Test procedures
First, rewind the micro-duct onto a cable drum and blow
the cable into the duct.
Then, soak the 80m-long micro-duct (with cable inside)
in a pool for 24 hours to make sure that the duct is
completely filled with water, as shown in Figure 1.
After that, seal the duct with end caps before taking the
cable drum out of the pool. Finally, put the cable drum
into the temperature cycling chamber to perform the
temperature cycling test.
Before that, record the attenuation of each fibre at room
temperature (23°C).
3.2 Temperature cycling programme
The temperature cycling programme is set as follows (one
cycle):
1 Lower the temperature from 23°C to 3°C within 30
minutes and hold this temperature for eight hours.
2 Then lower the temperature to -40°C within 30
minutes and hold it until the water is completely
frozen and the ice temperature is -10°C or lower (by
using a temperature monitoring device).
3 Raise the temperature to -2°C and hold this
temperature for one hour.
4 Raise the temperature to 65°C. Maintain the
temperature until the water reaches 15°C. Then,
return the temperature to 23°C and hold the
temperature until the water reaches 23°C ±5°C.
At every stage of temperature cycling test, record the
attenuation of each fibre.
3.3 Results
After the test, attenuation changes of all fibres are
really small. The largest attenuation values at -2°C are
shown in Figure 2, at 1,310nm and 1,550nm wavelengths
respectively.
3.4 Additional test
Considering extremely cold weather conditions, the
temperature cycling programme is changed and the above
test is repeated.
3.4.1 Temperature cycling programme (for extremely cold
weather)
1 Lower the temperature from 23°C to -40°C within
30 minutes and hold this temperature for 12 hours.
Perform attenuation measurement
2 Raise the temperature to 65°C within 30 minutes
and hold it for 12 hours. Perform attenuation
measurement
3 Return the temperature to 23°C within 30 minutes
and hold this temperature for 12 hours. Perform
attenuation measurement
❍
❍ Figure 2: OTDR graphs of the fibre with largest attenuation
values at -2ºC
❍
❍ Figure 3: OTDR graphs of the fibre with the largest attenuation
values at -40ºC