Ethernet Cabling For Monitoring, Supervisory, And Unit Control Layers - GE Mark VIe System Manual

3.7 Ethernet Cabling for Monitoring, Supervisory, and
Unit Control Layers
3.7.1 Single-mode Fiber
Note Trunks tie edge switches to the root switch.
For new sites, single-mode fiber-optic (SMF) cables are installed for all trunks. The main advantages of fiber-optic
transmission are as follows:
Note For more information, refer to Fiber-optic Cable and Patch Panel Selection (GHT-200001).
• Fiber segments can be longer than copper because the signal attenuation per foot is less.
• In high-lightning areas, copper cable can pick up currents, which can damage the communications electronics. Since the
glass fiber does not conduct electricity, the use of fiber-optic segments avoids pickup and reduces lightning-caused
outages.
• Grounding problems are avoided with optical cable. The ground potential can rise when there is a ground fault on
transmission lines, caused by currents coming back to the generator neutral point, or lightning.
• Optical cable can be routed through a switchyard or other electrically noisy area and not pick up any interference. This
can shorten the required runs and simplify the installation.
• Fiber-optic connections normally have higher signal levels and decreased chances of packet discard from noise
corruption. Typical differences in error rate is 10000 lower for fiber-optic cables.
• The cost per connection for fiber may now be less than copper cables. Large, multifiber trunk cables contain many fibers,
so cost per foot for each connection may actually cost less than multiple copper cables.
• Fiber-optic cable with proper jacket materials can be run buried in trays or in conduit.
• High-quality fiber-cable is light, tough, and easily pulled. With careful installation, it can last the life of the plant.
3.7.1.1 SMF Specifications
• Single-mode fiber-optic cables are connected from the root switch group to the edge switch group, providing redundancy.
Refer to the figure, Mesh Root and
• SMF cable lengths are less than or equal to 15 km (9.32 mi).
• SMF cables must be terminated and/or spliced by a certified fiber-optic cable installer. SMF cables cannot be terminated
and/or spliced by requisition or field engineers.
• SMF cables are 8.3/125 µm Core/Cladding diameter with a numeric aperture of 0.13.
94 GEH-6721_Vol_I_BP
Edges.
GEH-6721_Vol_I Mark VIe and Mark VIeS Control Systems Volume I
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