Designing A Distributed D20 Network - GE D20 Technical Overview

GE Grid Solutions

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, D.20 Link Installation.
D20 modules are configurable in star- or daisy-chain networks. Refer to Figure 38 for an
example of a D.20 Link configuration.
Example D.20
Power/
Configuration
RS485
Cables
Termination
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
GE Information
D20
Power/
RS485
Cables
D20A
D20S
D20K
DCI or DFS
D20A
D20S
Figure 38 D.20 Link Example Configuration
D20/D200 Technical Overview
Power/
RS485
Optional
Cables
Fiber Repeater
Power Supply
DCI or DFS
DCI
PFO or GFO Cable
(1 of 4 links, if DFS)
Legend
DCI - D.20 Communications Interface
DFS - D.20 Fiber Splitter
PRPI-019-3.00-10
Remote I/O
Power Supply
D20S
D20C
DCI
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