Date Code 20171021 Instruction Manual SEL-421 Relay
SEL-421 RelayInstruction Manual
SECTION 10
Communications Interfaces
Section 15: Communications Interfaces through Section 18: Synchrophasors in
the SEL-400 Series Relays Instruction Manual describes the various communica-
tions interfaces and protocols used in SEL-400 series relays. This section
describes aspects of the communications protocols that are unique to the
SEL-421. The following topics are discussed:
➤ Communications Database on page 10.1
➤ DNP3 Communication on page 10.8
➤ IEC 61850 Communication on page 10.22
➤ Synchrophasors on page 10.30
Communications Database
The SEL-421 maintains a database to describe itself to external devices via the
Fast Message Data Access protocol. This database includes a variety of data
within the relay that are available to devices connected in a serial or Ethernet net-
work. The database includes the regions and data described in Tab le 10.1 . Use the
MAP and VIEW commands to display maps and contents of the database
regions. See Section 9: ASCII Command Reference for more information on the
MAP and VIEW commands.
Data within the regions are available for access by external devices via the SEL
Fast Message protocol.
The LOCAL region contains the device FID, SID, and RID. It will also provide
appropriate status points. This region is updated on settings changes and when-
ever monitored status points change (see Table 10.2).
Table 10.1 SEL-421 Database Regions
Region Name Contents Update Rate
LOCAL Relay identification data including FID,
Relay ID, Station ID, and active protec-
tion settings group
Updated on settings change and
whenever monitored values
change
METER Metering and measurement data 0.5 s
DEMAND Demand and peak demand measurement
data
15 s
TARGET Selected rows of Relay Word bit data 0.5 s
HISTORY Relay event history records for the 10
most recent events
Within 15 s of any new event
BREAKER Circuit breaker monitor summary data 15 s
STATUS Self-test diagnostic status data 5 s
ANALOGS Protection and automation math variables 0.5 s
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