U.6.37
Date Code 20020501
User’s Guide
SEL-421/SEL-421-1 Relay
Testing and Troubleshooting
Relay Self-Tests
Relay Self-Tests
The SEL-421 Relay continuously runs many self-tests to detect out-of-
tolerance conditions. These tests run at the same time as relay protection and
automation logic, but do not degrade SEL-421 Relay performance.
Status Warning
and Status Failure
The relay reports out-of-tolerance conditions as a status warning or a status
failure. For conditions that do not compromise relay protection, yet are
beyond expected limits, the relay issues a status warning and continues to
operate. A severe out-of-tolerance condition causes the relay to declare a
status failure and enter a protection-disabled state. During a protection-
disabled state, the relay suspends protection element processing and trip/close
logic processing and deenergizes all control outputs. When disabled, the
ENABLED front-panel LED is not illuminated.
The relay signals a status warning by pulsing the HALARM Relay Word bit
(hardware alarm) to logical 1 for five seconds. For a Status Failure, the relay
latches the HALARM Relay Word bit at logical 1. To provide remote status
indication, connect the ‘b’ contact of OUT108 to your control system remote
alarm input and program the output SEL
OGIC
control equation to respond to
NOT (SALARM OR HALARM). See
Alarm Output on page U.2.42 in the
on connecting this alarm output for the SEL-421 Relay.
If you repeatedly receive status warnings, check the relay operating conditions
as soon as possible. Take preventive action early during the development of
potential problems to avoid system failures. For any status failure, contact
your Technical Service Center or the SEL factory immediately (see
The relay generates an automatic status report at the serial ports for a self-test
status failure if you set Port setting AUTO := Y. The relay issues a status
message with a format identical to the STATUS command output (see
except that the power supply information from the STA A response is
included after the SEL
OGIC
control equation error messages.
The relay also displays status warning and status failure automatic messages
on the front-panel LCD. Use the serial port
STATUS
and
CSTATUS
commands, the
AC
SEL
ERATOR
HMI Status button, and the front-panel
RELAY STATUS menu to display status warnings and status failures. See
STATUS on page R.8.45 in the Reference Manual
page U.4.12 in the User’s Guide
, and
RELAY STATUS on page U.5.24 in the
for more information on automatic status notifications and on
viewing relay status.
Status
is a sample
STATUS
screen from the Status option
of the
AC
SEL
ERATOR
HMI > Meter and Control tree view (the terminal
STATUS
report is similar).
STATUS A
report
showing all status information on a terminal.
Firmware Version Number
At the top of each status report the relay displays the present firmware version
number that identifies the software program that controls relay functions. The
firmware version is the four-place designator immediately following the relay
model number (the first characters in the firmware identification string). The
first character in the four-place firmware version number is “R” (representing
Summary of Contents for SEL-421
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