Date Code 20010518 Message Strings 8-9
SEL-2020 Instruction Manual
Table 8.6: Pre-Defined Strings for General-Purpose
User-Defined Commands with SEL IEDs
String Comment
20EVENT Recognize summary event reports received from SEL relays and trigger
with delay. Will continue to re-trigger until all reports are collected.
20EVENTQ Recognize summary event reports received from SEL relays and trigger
immediately.
20STATUS Recognize status messages received from SEL relays.
20GROUP Recognize group switch messages from SEL relays.
20EVENT FEATURES
Because SEL relays may trigger multiple event reports in rapid succession, the SEL-2020 has
special features based on these triggers to facilitate collecting event reports. To take advantage
of these special features, you must set 20EVENT as a user-defined command with SET U. The
SEL-2020 then keeps track of the number of summary event reports received from the SEL relay
on that port. You must then set MESG3 or MESG3A to 20EVENT, 20EVENTS, or 20EVENTL.
The SEL-2020 will then collect the oldest unread event report from the SEL relay. The CMDx
bit corresponding to the 20EVENT command will continue to retrigger every 5 minutes as long
as there are uncollected event reports. (To have the CMDx bit trigger immediately on each
unsolicited summary event report, use the user-defined command 20EVENTQ.) The number of
reports left to read is visible in the Local region of the port database.
These features can be used to collect and process event reports in a number of ways. Examples
4, 5, and 6 in Section 4: Job Done Examples illustrate using these features to collect event
reports into archive memory, to print them, and, once a day, to call out to a remote computer to
upload the event reports. The following example illustrates collecting event reports and calling
them out when you do not have archive memory installed. Consider a relay on Port 1 and
modem on Port 8 with the following settings:
SET U 1
CMD1=20EVENT
SET A 1
ISSUE3=CMD1*!8:D1
MESG3=20EVENT
SET A 8
ISSUE1=!1:D3
MESG1=“\IATDT15093321890/\F1:D3/”
Consider what happens when the relay triggers three event reports in rapid succession. The
1:CMD1 bit triggers collection of an event report. Because the SEL-2020 received three
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