![Schweitzer Engineering Laboratories SEL-421-4 Instruction Manual Download Page 1100](http://html.mh-extra.com/html/schweitzer-engineering-laboratories/sel-421-4/sel-421-4_instruction-manual_12167261100.webp)
10.4
SEL-400 Series Relays
Instruction Manual
Date Code 20171006
Testing, Troubleshooting, and Maintenance
Testing Philosophy
Maintenance Testing
All SEL-400 series relays use extensive self-testing routines and feature detailed
metering and event reporting functions. These features reduce your dependence
on routine maintenance testing. When you want to perform maintenance testing,
follow the recommendations in
.
You can use the relay reporting features as maintenance tools. Periodically com-
pare the relay
METER
command output to other meter readings on a line to ver-
ify that the relay measures currents and voltages correctly and accurately. Use the
circuit breaker monitor, for example, to detect slow breaker auxiliary contact
operations and increasing or varying breaker pole operating times. For details on
these features, see
Circuit Breaker Monitor on page 8.1
.
Each occurrence of a fault tests the protection system and relay application.
Review relay event reports in detail after each fault to determine the areas need-
ing your attention. Use the event report current, voltage, and relay element data to
determine that the relay protection elements and communications channels oper-
ate properly. Inspect event report input and output data to determine whether the
relay asserts outputs at the correct times and whether auxiliary equipment oper-
ates properly.
At each maintenance interval, the only items to be tested are those that have not
operated (via fault conditions and otherwise) during the maintenance interval.
The basis for this testing philosophy is simple: you do not need to perform fur-
ther maintenance testing for a correctly set and connected relay that measures the
power system properly and for which no relay self-test has failed.
SEL-400 series relays are based on microprocessor technology; the relay internal
processing characteristics do not change over time. For example, if time-overcur-
rent element operating times change, these changes occur because of alterations
to relay settings and/or differences in the signals applied to the relay. You do not
need to verify relay element operating characteristics as a part of maintenance
checks.
SEL recommends that you limit maintenance tests on SEL relays according to
the guidelines listed in
. You will spend less time checking relay oper-
ations that function correctly. You can use the time you save to analyze event data
and thoroughly test systems needing more attention.
Table 10.3
Maintenance Testing
Details
Description
Time
Test at scheduled intervals or when there is an indication of a problem with the
relay or power system.
Goals
a) Confirm that the relay is measuring ac quantities accurately.
b) Check that scheme logic and protection elements function correctly.
c) Verify that auxiliary equipment functions correctly.
Tests
Test all relay features/power system components that did not operate during an
actual fault within the past maintenance interval.
Summary of Contents for SEL-421-4
Page 6: ...This page intentionally left blank ...
Page 14: ...This page intentionally left blank ...
Page 30: ...This page intentionally left blank ...
Page 104: ...This page intentionally left blank ...
Page 128: ...This page intentionally left blank ...
Page 536: ...This page intentionally left blank ...
Page 584: ...This page intentionally left blank ...
Page 616: ...This page intentionally left blank ...
Page 696: ...This page intentionally left blank ...
Page 750: ...This page intentionally left blank ...
Page 755: ...Instruction Manual PM400 01 NB SEL 400 Series Relays Instruction Manual 20171006 ...
Page 776: ...This page intentionally left blank ...
Page 932: ...This page intentionally left blank ...
Page 976: ...This page intentionally left blank ...
Page 1024: ...This page intentionally left blank ...
Page 1038: ...This page intentionally left blank ...
Page 1064: ...This page intentionally left blank ...
Page 1128: ...This page intentionally left blank ...
Page 1206: ...This page intentionally left blank ...
Page 1316: ...This page intentionally left blank ...
Page 1350: ...This page intentionally left blank ...
Page 1464: ...This page intentionally left blank ...
Page 1468: ...This page intentionally left blank ...
Page 1492: ...This page intentionally left blank ...
Page 1518: ...This page intentionally left blank ...