WCA March 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. ❍ ❍ Figure 2 : OTDR graphs of the fibre with largest attenuation values at -2ºC

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 3 : OTDR graphs of the fibre with the largest attenuation values at -40ºC

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Wire & Cable ASIA – March/April 2017