Omron CS1W-CLK12-V1, Operation Manual

Page: 303 / 312

286
Handling and Using GI Cable Appendix D
Maintaining the Optical Fiber Cables
Locating Faults in the Cables
After the Optical Fiber Cable has been installed, obstructions in the fibers can occur due to accidental damage
or changes in the operating environment. A fault locator is used to locate these optical obstructions.
The fault locator is a measuring device that indicates the amount of transmission loss and the distance to con-
nections/fractures in the optical fiber from the strength and timing of light back-scattered from those points.
A fault indicator will show slight increases in transmission loss caused by damaged points, so damage can be
discovered very quickly. The following diagram shows how a fault locator operates.
Incident light pulse
Fused connection
Received
light level
Received light
Connector
Fresnel reflection at
connector surface
Fracture
Fresnel reflection
at initial surface
Loss at fused
connection
Propagation delay:
τ
(Fiber length:
l
km)
Back-scattered
light
Fresnel reflection
at fracture