Rockwell Automation SA3100 Fiber-Optic Cabling-Distributed Pwr System - Manual (Page 15)

Fiber-Optic Link Installation 3-1
C
HAPTER
3
Fiber-Optic Link Installation
The fiber-optic link installation should conform to all applicable codes.
3.1 Optical Power Budget
Fiber-optic communication depends on the launched light signal reaching the receiver
at a level high enough to be detected. A power budget calculation determines the
amount of losses present in the fiber-optic link and the result is then compared to the
total amount of optical power available from the fiber-optic transmitter. The transmitter
must be capable of launching more optical power than what is lost in the system. The
total amount of optical power (power budget) provided by the fiber-optic transmitters is
2.6dB which includes the losses of the connectors on the module faceplates. The
maximum cable length is 750 meters (2500 feet) with 62.5 micron cable and 200
meters (660 feet) with 50 micron cable. The minimum cable length for both 62.5
micron cable and 50 micron cable is 1 meter (3.3 feet).
A sample fiber-optic link for power budget calculations is shown in figure 3.1.
As shown in figure 3.1, the sample fiber-optic link is composed of three segments: the
end segments are 4.5 meters long while the middle segment is 300 meters. Since the
power budget value (2.6dB) has factored in one connector pair already, only two more
connector pairs have to be accounted for in the power budget calculation.
!
ATTENTION: The user is responsible for conforming with all applicable
local, national, and international codes. Failure to observe this precaution
could result in damage to, or destruction of, the equipment.
Figure 3.1 – A Sample Fiber-Optic Link for Power Budget Calculations
UDC Module PMI
XMT
RCV
XMT
RCV
COMM
A
COMM
B
4.5m 300m 4.5m
Cable
Segment
Cable
Segment
Connectors Connectors
XMT
RCV
Cable Segment