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16.22
SEL-400 Series Relays
Instruction Manual
Date Code 20171006
DNP3 Communication
DNP3 Documentation
ting) time. When the EVELOCK setting is zero, single-event mode effectively
acts as a zero-buffer FIFO queue. In this mode, relay events are presented to gen-
erate DNP3 events for the fault summary analog inputs as they occur. Fault sum-
mary analog inputs shall be reset to 0 on a rising edge of RSTDNPE (Global
SEL
OGIC
equation result). The relay element EVELOCK shall be set when a
relay event is triggered and reset when EVELOCK time expires.
Multiple-Event Mode
Relay multiple-event summary data can be read in two ways: first in, first out
(FIFO); or last in, first out (LIFO).
and
below for procedures to
retrieve relay events that occur when FLOC is in range of MINDIST and MAX-
DIST. Event retrieval as shown below is a manual monitor, control, and poll pro-
cess. A DNP3 master can collect relay event summaries using event data rather
than the static data polling described below. For best results, the master must con-
trol the NXTEVE binary output no faster than once every two seconds to load a
new event into the event summary analog inputs. If the NXTEVE binary output is
controlled at a faster rate, some DNP3 events may not be recognized and pro-
cessed by the DNP3 event scanner.
FIFO
Multiple-event FIFO mode shall be initiated if the DNP3 session master operates
the NXTEVE (next event) control. The master should monitor the UNRDEV
binary input point, which will be asserted when there is an unread relay event
summary. The NUNREV bit will also be asserted as long as there remain any
unread events newer than the currently loaded event summary. To read the oldest
unread relay event summary, the master should send a close, latch on, or pulse-on
control to the NXTEVE binary output point. This will load the relay event sum-
mary analogs with information from the oldest relay event summary, discarding
the values from the previous load.
After reading the analogs, the master should again check the UNRDEV binary
input point, which will be on if there is another unread relay event summary. The
master should continue this process until the UNRDEV binary input point deas-
serts. If the master attempts to load values by controlling the NXTEVE output
point when the UNRDEV binary input point is deasserted, the relay event type
analog (FTYPE) will be loaded with zero. With the FIFO method, the relay event
summaries will always be collected in chronological order.
LIFO
Multiple-event LIFO mode event summary retrieval is similar to FIFO retrieval,
with the following difference: to read the newest unread relay event summary, the
master should send a latch off control to the NXTEVE binary output point. As
with FIFO retrieval, the master should monitor the UNRDEV binary input to
determine if there are any unread events. Users must be aware of one caveat with
LIFO retrieval: if an event occurs while in the process of reading the newest
event(s) event collection will no longer continue in reverse chronological order.
The next event read will be the newest event, and will proceed with the next new-
est, but any events that have already been read shall be skipped. The NUNREV
bit will be asserted if this happens, signifying that the currently loaded event
summary is no longer the newest event.
Summary of Contents for SEL-421-4
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