System information

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February 2009
Power Management Systems & Products
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Sheet 02
Power Xpert Systems and Network System Expansion
Application Information
031
Conventional electrical data signals
are converted into a modulated light
beam, introduced into the fiber and
transported via a very small diameter
glass or plastic fiber to a receiver that
converts the light back into electrical
signals.
Optical fibers allow data signals to
propagate through them by ensuring
that the light signal enters the fiber at
an angle greater than the critical angle
of the interface between two types of
glass. Optical fiber is actually made
up of three parts. The center core is
composed of very pure glass. Core
dimensions are usually in the range
of 50 to 125 um for multi-mode cables
and 8-9 um for single-mode cables.
The surrounding glass, called clad-
ding, is a slightly less pure glass.
The diameter of the core and cladding
together is in the range of 125 to
440 um.
Surrounding the cladding is a protec-
tive layer of flexible silicone called
the sheath.
Fiber Optic Cable
Wiring Guidelines
The following information can be used
as a guide when designing an Ethernet
system using Fiber Optic Ethernet
Cable:
■ Select a fiber cable that is suited for
the application, e.g., outdoor, aerial,
duct, intra-building, risers, general
building and plenum applications.
■ Fiber optic cable is useful in applica-
tions where the environment is com-
bustible, electrically noisy, the cable
must be bundles with high voltage
wires or where common mode volt-
ages may exist between the earth
ground points of the terminating
connectors.
■ Fiber optic cable is available in vari-
ous operating temperature ranges.
Care should be taken to match the
temperature rating of the fiber to the
environment it will be exposed to.
The temperature specification for
fiber may be narrower than copper
cable. Consult the cable manufac-
turer for temperature specifications
of your cable type.
■ Sealed fiber connectors are available
for use in harsh environments to
prevent contamination from enter-
ing the connector and fiber. The type
of seal required will be application
dependant and can vary from dust-
and moisture-proof to water-tight.
■ Mixing fiber cable types is not per-
mitted. The same core dimensions
and mode must be used within
cable segments.
■ Care should be taken when purchas-
ing connectors to include strain
relief which reduces mechanical
strain (vibration) within the cable, as
well as the connector. Strain relief
also provides support to the cable
to ensure proper bend radius at the
connector.
■ Single-Mode Fiber is used for long
distance transmission of up to
120 km. Distance may vary depend-
ing on speed and type of converter
used.
■ Multi-Mode Graded-Index Fiber
Cable is used for communication
over shorter distances of up to 2 km.
■ Fiber cable is composed of glass and
is not well suited for applications
requiring tight bend radiuses. Cable
radius dimensions vary per manu-
facturer. If the manufacturer does
not provide a bend radius, a typical
rule of thumb is a radius not less
than 15x the cable diameter.
■ Fiber cable to connector termina-
tions can be performed in the field
using special equipment. This
method is not recommended.
❑ Tier One testing is recommended
when diagnosing system irregu-
larities and should be performed
in all new installations
❑ Tier Two testing is recommended
to certify that a system complies
with standards set forth by the
owner/installer