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Chapter 5: How to choose the right optical fiber cable
Parameters
General outline of the parameter involved in choosing the rigth optical fiber cable design.
First parameter: the optical fiber
The four most common types of fiber in fiberoptic networks today (no specific order).
Primary coating
Application of acrylate as the primary coating.
Acrylate as the primary coating
Primary coated fiber.
The fiber characteristics after primary coating application
The most common geometrical parameters for standard single-mode fiber 8–10/125 μm.
Maximum permissible stresses on a primary coated fiber.
Color-coding for optical fibers
Color-coding scheme used by Telia AB, Sweden.
Second parameter: the buffers
Loose tube buffer (loose fibers/ribbons in tube)
A number of primary coated fibers or ribbons can lie loosely in a tube, which functions as a loose tube buffer.
Temperature variations
The fibers can move freely within the loose tube buffer to compensate for temperature variations.
Areas of application for tight buffered fibers
Fiber with tight buffer.
Tight buffered fibers
Fiber ribbon technique: Encapsulating
The three most common methods of manufacturing fiber ribbon.
Encapsulated ribbon fiber
Manufacture
Encapsulated fiber ribbon. The illustration shows a fiber ribbon with one layer of acrylate applied over primary coated fibers.
Tests
Macrobend test
Setup for macrobend test.
Torsion test
Setup for torsion test.
Crush test
Setup for crush test.
Process testing
Strippability - random testing
Example of good strippability (upper) and bad strippability (lower).
Separability - random testing
Each individual fiber must be able to separate without damage to the individual primary coatings.
Fiber curl
Fiber curl.
Attenuation
Graphs showing OTDR attenuation plot at both 1310 nm and 1550 nm.
Geometry
Geometry of a four fiber ribbon.
Parameters regarding the geometry of the fiber ribbon.
Third parameter: the strength member
Aramide yarn
Different types of strength member.
Fourth parameter: the cable core
Cables with circular core
Optical fiber cable, concentric construction, with loose tubes around the central strength member.
Cable illustrated is the GRHLDV.
Optical fiber cable; concentric construction with tight buffered fibers around the central strength member. Cable illustrated is the GNHLBDUV.
Cable with slotted core
Slotted core profiles. From left to right S, Z and SZ stranding.
Three different types of slot profile.
Pitch of a slotted core cable
Fibercreep due to temperature changes.
Expansion and contraction of cables
The fiber can move freely.
Expansion and contraction caused by temperature variations
Young's modulus, density and coefficient of linear thermal expansion of various materials used in optical fiber cables.
Four examples of optical fiber cables with slotted core. Cables illustrated are from the left: GRSLDV, outdoor cable with loose tube buffer.
GNSLBDV, indoor/outdoor cable with tight buffered fibersGASLDV, outdoor cable with four fiber ribbon
GASLDV, outdoor cable with eight fiber ribbon.
Optical fiber cable without a core
The simplest optical fiber cable design is suitable for connecting cables and in data
networks. The cable illustrated is GNLBDU.
With a multiple of subcables and an extra sheath, this cable becomes a neat package of 24 GNLBD cables measuring only 15 mm in
diameter. The cable illustrated is GNHLLBDU.
Fifth parameter: the water protection
Metallic tube: Copper encapsulation
Copper plate formed to a tube and electrically welded to a water-proof encapsulation.
Sixth parameter: sheathing
The sheath has primarily the following functions:
• Provides mechanical protection
• Provides thermal insulation
• Protects against chemicals
• Provides moisture protection
• Protects from rodents.
The plastic materials normally used for the sheath are:
• Standard polyethylene (PE)
• Flame retardant halogen-free materials
• Polyvinyl chloride (PVC)
• Polyamide (PA)
• Fluoroplastics
• Polyurethane (PU)
• Copper tube (Cu)
Applying the final sheath:
Seventh parameter: extra reinforcement
Corrugated steel tape
Corrugated steel tape-reinforced cable for laying underground, or in ducts. The cables illustrated are GRSLWLV and GASLWLV.
Steel wire, steel tape
Steel-reinforced cable for laying underground, e.g., by direct ploughing. The cable illustrated is GRSLTLV.
HET - heat expandable tape
By using dielectric reinforcement, a completely metal-free cable can be manufactured for direct ploughing or laying underground. This cable is ideal for installations located in the
vicinity of high voltage lines. The cable illustrated is GASLLDV, 192 fibers.
Aramide yarn
Aramide yarn is used as longitudinal reinforcement in aerial cable for spans up to
250 m. The cable illustrated is GRLSDV.
Aerial cable with a large amount of of aramide yarn as strength member. This type of cable is self suporting for spans up to 1 000 m. Cable
illustrated is the SkyspanTM (Focas Inc.).
Suspension strands
With a steel suspension strand, optical fiber cable can be suspended in spans of 50 - 70 m. The cable illustrated is GASLCV.
Optical ground wire, OPGW
Optical power ground wire to replace the traditional ground wire on topof power lines. Cable illustrated is thr SkyliteTM (Focas Inc.).
Hybrid cables
Two examples of hybride cable designed to be installed alongside the railway tracks.
A collection of newer types of cables
Cable to be wrapped around ground wire or phase line
”Skywrap“.
Indoor cable with fiber ribbon, suited for FTTH etc.
Outdoor cable with loose tube suited for FTTH etc.
Ribbon cable with 432 fibers.
Ribbon cable with 864 fibers.