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A-57
IM 39J06B40-01EN 14th Edition: May 30, 2022
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Minimum bending radius
Optical fibers and optical fibers have stipulated minimum bending radius. Consider this
property when selecting sensor optical fibers for an intended installation.
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Precautions on Usage and Installation
In addition to the above general precautions, the following usage and installation
precautions must be observed.
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No reflection
The sensor optical fiber must be reflection free. Thus fusion splicing must be used and
the optical fiber far end must include anti-reflection termination, which may be achieved
through an angled cleave or a fused connector. For single-ended measurement, a large
optical loss on the far end of the sensor optical fiber is fine. (For instance, a terminator
can be installed).
An optical fiber can also be checked for reflection from the optical loss distribution profile
of the ST or AS wavelengths measured with the DTSX3000.
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Connection loss
If it is necessary to splice optical fibers together, minimize connection loss at the splice
point and keep it within 0.3 dB. If the measured connection loss exceeds 0.3 dB, redo
the splicing. Connection loss can be checked from the optical loss distribution profile of
the ST or AS wavelengths measured with the DTSX3000.
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Bending loss
Optical fibers and optical fibers have their own minimum bending radius. Ensure that laid
optical fibers satisfy these requirements. Pay special attention when optical fibers must
be bent within a tight space. If the requirements are not satisfied, the optical fibers and
optical fibers may exhibit larger loss, leading to unstable distributed temperature
measurement.
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Stress
Optical fibers (and sensor optical fibers) used must satisfy the maximum stress
requirement. Excessive stress will cause torsion and thus increase optical loss or even
shorten the optical fiber service life.
Pay special attention to the bending radius and the stress of a sensor optical fiber at its
exit from the optical connector which is connected to the DTSXL System. If the DTSXL
System is installed in a cabinet, ensure that the cabinet door does not touch the optical
fibers when the door is closed.
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Darkening
Optical fibers (and sensor optical fibers) have service life, which is affected by
temperature and humidity. For example, a sensor optical fiber with a service life of 20
years under normal temperature-humidity conditions may suffer darkening and
deteriorate much earlier under high-temperature, high-humidity conditions. The rate of
deterioration depends on the optical fiber used and the usage environment. If optical
fibers are used under unfavorable conditions, replace them regularly just like
consumables. Optical fiber darkening leads to optical fiber loss increase, which varies
with optical wavelengths and in turn adversely affects the temperature resolution and
temperature measurement accuracy of the DTSX3000. While minor darkening may be
compensated through temperature calibration with the DTSX3000, more severe
darkening will necessitate optical fiber replacement.