GE Grid Solutions
D20/D200 Technical Overview
GE Information
PRPI-019-3.00-10
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2.8.1 Designing a Distributed D20 Network
To set up a distributed D20 peripheral I/O network design, three key factors need to be
considered:
•
Peripheral configuration of each remote location
•
Approximate distance between peripheral locations
•
Type of cable (RS-485 serial, plastic fiber, or glass fiber)
Generally, an RS-485 serial link is used for short distances, such as between D20 modules
located close together on a rack or mounted in a group, and a fiber optic link is used to extend
the D.20 Link to remotely located modules or in electrically noisy environments. When the D.20
Link is installed outside the substation control house, GE Grid Solutions highly recommends the
use of a fiber optic cable.
For more information on planning a D.20 Link, refer to Appendix G,
D20 modules are configurable in star- or daisy-chain networks. Refer to Figure 38 for an
example of a D.20 Link configuration.
Legend
DCI - D.20 Communications Interface
DFS - D.20 Fiber Splitter
D20A
DCI or DFS
D20K
D20S
D20
Power/
RS485
Cables
DCI
DCI or DFS
Power Supply
Power/
RS485
Cables
(1 of 4 links, if DFS)
PFO or GFO Cable
Power Supply
DCI
D20C
D20S
Power/
RS485
Cables
Example D.20
Configuration
Optional
Fiber Repeater
Remote I/O
D20A
D20S
Termination
Figure 38 D.20 Link Example Configuration
To interconnect D20 modules with an RS-485 serial link or a fiber optic link, certain
communications equipment is needed:
•
D.20 Communication Interface or D.20 Fiber Optic Splitter with a fiber optic adaptor
between the D20 main processor (or the last peripheral on an RS-485 serial link), and the
start of the fiber optic link