U.4.39
Date Code 20020501
User’s Guide
SEL-421/SEL-421-1 Relay
Basic Relay Operations
Reading Oscillograms, Event Reports, and SER
Reading Oscillograms, Event Reports, and SER
The SEL-421 Relay has great capabilities for storing and reporting power
system events. These include high-resolution oscillography with sampling as
high as 8 kHz, event reports that encompass important variables in the power
system, and the SER that reports changing power system conditions and relay
operating states.
You can view oscillograms taken from high-resolution raw data or from
filtered event report data. Each type of presentation gives you a unique view
of the power system. High-resolution oscillograms are useful for viewing
system transients and dc artifacts outside the relay filter system; event report
oscillograms give you a picture of the quantities that the relay used in the
protection algorithms.
The examples listed in this subsection give step-by-step procedures to
acquaint you with these features.
Section 3: Analyzing Data in the
gives a complete discussion of these relay features.
Generating an Event
To view high-resolution raw data oscillograms and event reports, you must
generate a relay event. High-resolution oscillography and event reports use the
same event triggering methods. The relay uses three sources to initiate a data
capture: Relay Word bit TRIP asserts, SEL
OGIC
control equation ER (event
report trigger), and the
TRI
command. (Factory default setup no longer
includes the
PUL
command as an event report trigger. You can add the
PUL
command by entering the Relay Word bit TESTPUL in the ER SEL
OGIC
control equation.) See
Test Commands on page U.6.6 in the User’s Guide
Triggering an Event
You can use an event trigger to initiate capturing power system data. The
procedure in the following steps shows how to use the
AC
SEL
ERATOR
HMI to
generate the
TRI
command, which triggers an event capture. In this example,
the relay uses default parameters to record the event. These parameters are at a
sampling rate (SRATE) of 2000 samples per second (2 kHz), a pretrigger or
prefault recording length (PRE) of 0.1 seconds, and an event report length
(LER) of 0.5 seconds. See
Duration of Data Captures and Event Reports on
page A.3.6 in the Applications Handbook
for complete information on
changing these default settings to match your application.
This example assumes that you have successfully established communication
with the relay; see
Making an EIA-232 Serial Port Connection on page 4.6
for
a step-by-step procedure. In addition, you must be familiar with relay access
levels and passwords. See
Changing the Default Passwords: Terminal on
to change the default access level passwords. You should also be
familiar with the
AC
SEL
ERATOR
software. See
. In addition, you should perform
to connect secondary test voltages and currents, and to set the relay
to meter these quantities correctly.
Step 1. Connect voltage and current sources to the relay secondary
voltage and secondary current inputs. Use the connections of
View Metering: Terminal on page 4.31
or
Summary of Contents for SEL-421
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