10.16
SEL-421 Relay Instruction Manual Date Code 20171021
Communications Interfaces
DNP3 Communication
In either mode, DNP3 events for all event summary analog inputs (see
Table 10.11) will be generated if any of them change beyond their dead band
value after scaling (usually whenever a new relay event occurs and is loaded into
the event summary analog inputs). Events are detected approximately twice a
second by the scanning process.
See Table 10.12 and Table 10.13 for the components of the FTYPE analog input
point. The single bit asserted in the upper byte indicates the event cause (Trigger,
Trip, or ER element). The bit(s) asserted in the lower byte indicate which
phase(s) were affected by the fault. If no bits are asserted in the upper byte, there
is no valid fault summary loaded. If no bits are asserted in the lower byte, the
affected phase could not be determined.
Lower byte bits will be set according to the event’s affected phases. For example,
a three-phase fault will set bits 0, 1, and 2, for a decimal value of 7. If this event
caused a trip, the upper byte would also have bit 2 set, for a total decimal value of
1031 (0407 in hexadecimal).
Default Data Map
Table 10.14 shows the SEL-421 default DNP3 data map. The default data map is
an automatically generated subset of the reference map. All data maps are initial-
ized to the default values. If the default maps are not appropriate, you can also
use the custom DNP mapping commands SET D n and SHOW D n, where n is
the map number, to edit or create the map required for your application.
Table 10.12 Object 30, 32, FTYPE Upper Byte-Event Cause
Bit Position
Event Cause
7 6 5 4 3 2 1 0
No fault summary loaded
X Trigger command
X Trip element
X Event report element
Table 10.13 Object 30, 32, FTYPE Lower Byte-Affected Phase(s)
Bit Position
Affected Phase
7 6 5 4 3 2 1 0
Indeterminate
XA-Phase
XB-Phase
XC-Phase
X Ground
Table 10.14 SEL-421 DNP3 Default Data Map (Sheet 1 of 7)
Object Default Index Label Description
Binary Inputs
01, 02 0 RLYDIS Relay disabled
01, 02 1 TRIPLED Trip LED
01, 02 2 STFAIL Relay diagnostic failure
01, 02 3 STWARN Relay diagnostic warning
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