U.4.42
SEL-421 Relay User’s Guide Date Code 20090715
Basic Relay Operations
Reading Oscillograms, Event Reports, and SER
Reading Oscillograms, Event Reports, and SER
The SEL-421 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
Applications Handbook 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.6.5.)
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
ACSELERATOR
QuickSet 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.3.5 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 U.4.5).
In addition, you must be familiar with relay access levels and passwords (see
Changing the Default Passwords: Terminal on page U.4.9 to change the
default access level passwords). You should also be familiar with
ACSELERATOR QuickSet (see Checking Relay Status: ACSELERATOR QuickSet
on page U.4.11 and Section 3: PC Software). In addition, you should perform
View Metering: Terminal on page U.4.33 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 U.4.33 and Figure 4.25 or
Figure 4.26).
Courtesy of NationalSwitchgear.com
To Next Page
Loading...
