EoW March 2011

technical article

Attenuation increases at 70˚C and at the final 23˚C were not significant. For this reason, the attenuation increases that are presented in this paper are all measured at the –40˚C temperature extremes. Multiple fibres were tested in each cable sample. The average attenuation increase was calculated and the maximum individual measurement was identified. These are the values reported in this paper. Each cable sample was inspected for cable damage at the completion of the mid-span test. There was no physical damage found on any of the cable samples. 3 Acceptance criteria comparison There are also two sets of acceptance criteria that are associated with these two test methods. These two specifications are through the PE-90 document and the GR-20 document. Each specification is outlined below. The PE-90 specification and acceptance criteria is as follows: a) Mid-span opening for installation of loose tube single mode optical cable in pedestal shall be 6.096m (20ft) b) No greater than 0.1 dB attenuation increase (at 1,550nm) on any individual fibre and no greater than 0.05 dB attenuation increase average (at 1,550nm) on all of the fibres, during the last cycle at –40˚C and 70˚C c) No greater than 0.05 dB attenuation increase (at 1,550nm) on any individual fibre at the final 23˚C temperature

Attenuation requirements at 1,550nm

PE-90 GR-20

Expressed tube length

20ft

14ft

Maximum attenuation increase at last temperature extremes Average attenuation increase at last temperature extremes Maximum attenuation increase at final 23˚C temperature Average attenuation increase at final 23˚C temperature

0.1 dB

-

0.05 dB 0.15 dB

0.05 dB

-

-

0.15 dB

Table 2 ▲ ▲ : PE-90 and GR-20 mid-span test attenuation requirements comparison

Maximum attenuation increase (dB) at 1,550nm and –40ºC

PE-90 Cycle

Cable 1

Cable 2

Cable 3

Cable 4

1 2 3 4 5

0.02 1.34 1.11 1.73 1.25

0.02 0.02 0.03 0.02 0.02

0.007 0.417 0.653 0.577 0.575

0.02 0.87 0.70 0.74 1.01

20-ft PE-90 final cycle maximum 14-ft FOTP-244 maximum

1.25

0.02

0.575

1.01

0.59

0.01

0.311

0.31

Table 3 ▲ ▲ : 20 ft PE-90 & 14 ft draft FOTP-244 midspan test comparison at –40˚C

The tubes, cable and assemblies are also to be inspected at the final room temperature for any visual damage. A comparison of the two test methods is outlined in Table1 . During the course of the testing it was found that the only significant attenua- tion increases occurred at the –40˚C temperature extremes.

Soak times of three hours are required for all temperature extremes and for the final 23˚C temperature. All test fibres are to be measured at room temperature at the 1,550nm wavelength prior to temperature cycling. This is the reference measurement. The test fibres are then measured at the 1,550nm wavelength in the last cycle at the temperature extremes and at the final 23˚C temperature. Attenuation increases are calculated and evaluated against an upper specification limit. The tubes, cable and assemblies are also to be inspected at the final room temperature for any visual damage. FOTP-244 The FOTP-244 test method requires two complete cycles and a final 23˚C tem- perature soak. It requires 14 hours of soak for the first 70˚C temperature extreme. This extended soak time is intended to help release shrink-back stresses that may have been locked into the tubes during processing. All other soak times are required to be a minimum of one hour. All test fibres are measured at room temperature at the wavelength of 1,550nm before temperature cycling. This is the reference measurement. The test fibre attenuations are then measured at the 1,550nm wavelength at the last temperature cycle extremes and the end of the test, at room temperature.

Figure 1 ▼ ▼ : 20-ft PE-90 and 20-ft draft FOTP-244 midspan test comparison – average attenuation increase

Average attenuation increase (dB)

Cable 1 Cable 2 Cable 3 Cable 4 Cable 5 Cable 6

Cycle 1 Cycle 2 Cycle 3 Cycle 4 Cycle 5 20ft draft FOTP-244

119

EuroWire – March 2011