R.6.24
SEL-421 Relay Reference Manual Date Code 20111215
DNP3 Communications
DNP3 Documentation
Reading Relay
Event Data
The SEL-421 provides protective relay event history information in one of two
modes: single event or with a first-in, first-out (FIFO) multi-event access
method. The default mode is single event.
Single event mode provides the most recent tripping event. When a trigger
with a trip type (not ER and not TRIG) occurs with a the fault location in the
range of MINDIST to MAXDIST, this data shall be made available in the
DNP fault summary area, generating appropriate DNP events. (If MINDIST is
set OFF, then there is no minimum. Similarly, if MAXDIST is set OFF, there
is no maximum.) The relay shall than ignore any subsequent events for
EVELOCK (port setting) time. This data shall be reset to 0 on a rising edge of
RSTDNPE (global SELogic equation result). The relay element EVELOCK
shall be set when the fault is triggered and reset when EVELOCK time
expires.
Multi-event mode shall be initiated if the next event control is operated. The
master should monitor binary input point 1619 (MAPSEL := B; see
Tab le 6.10) or point 3 (MAPSEL := E; see Table 6.10), which will be asserted
when there is an unread relay event summary. To read the oldest relay event
summary, the master should pulse-on binary output point 41 (see Table 6.15).
This will load the relay event summary analogs (points 176 through 181
Tab le 6.10) with information from the oldest relay event summary, discarding
the values from the previous load.
After reading the analogs, the master should again check binary input point
1619 (point 3 when MAPSEL := E), which will be on if there is another
unread relay event summary. The master should continue this process until
binary input point 1619 (point 3 when MAPSEL := E) is deasserted. If the
master attempts to load values using output point 41 when binary input point
1619 (point 3 when MAPSEL := E) is deasserted, the relay event type analog
(point 176) will be loaded with zero. With the FIFO method, the relay event
summaries will always be collected in chronological order.
Control Point
Operation
Use the Trip and Close operations with Object 12 control relay output block
command messages to operate the points shown in Table 6.15. Pulse
operations provide a pulse with a duration of one protection processing
interval.
Table 6.13 Object 30, 32, Index 176 Upper Byte—Event Cause
Byte Value Description
1 Trigger command
4 Trip element
8 Event report element
Table 6.14 Object 30, I32, Index 176 Lower Byte—Fault Type
Bit Description
0 Indeterminate
1 A-phase
2 B-phase
4 C-phase
8 Ground
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