Schweitzer Engineering SEL-387-0, Instruction Manual

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10.33
Date Code 20170601 Instruction Manual SEL-387-0, -5, -6 Relay
Testing and Troubleshooting
Relay Troubleshooting
What to test: Anything not shown to have operated during an actual fault
within the past maintenance interval.
SEL relays use extensive self-testing capabilities and feature detailed metering
and event reporting functions that lower the utility’s dependence on routine
maintenance testing.
Use the SEL relay reporting functions as maintenance tools. Periodically
verify that the relay is making correct and accurate current measurements by
comparing the relay
METER output to other meter readings on that line.
Review relay event reports in detail after each fault. Using the event report
current and relay element data you can determine that the relay protection
elements are operating properly. Using the event report input and output data
you can determine that the relay is asserting outputs at the correct instants and
that auxiliary equipment is operating properly. At the end of your maintenance
interval, the only items that need testing are those that have not operated
during the maintenance interval.
The basis of this testing philosophy is simple: If the relay is correctly set and
connected, is measuring properly, and no self-test has failed, there is no reason
to test it further.
Each time a fault occurs, the protection system is tested. Use event report data
to determine areas requiring attention. Slow breaker auxiliary contact
operations and increasing or varying breaker operating time can be detected
through detailed analysis of relay event reports.
Because SEL relays are microprocessor based, their operating characteristics
do not change over time. Time-overcurrent and current differential element
operating times are affected only by the relay settings and applied signals. It is
not necessary to verify operating characteristics as part of maintenance
checks.
At SEL, we recommend that maintenance tests on SEL relays be limited under
the guidelines provided above. The time saved may be spent analyzing event
data and thoroughly testing those systems that require more attention.
Relay Troubleshooting
Inspection Procedure
Complete the following procedure before disturbing the relay. After you finish
the inspection, proceed to the
Troubleshooting Procedure .
Step 1. Do not turn the relay off.
Step 2. Check to see that the power is on.
Step 3. Measure and record the power supply voltage at the power
input terminals.
Step 4. Measure and record the voltage at all control inputs.
Step 5. Measure and record the state of all output relays.