Sel 551 - Section 8: Testing and Troubleshooting; Overview; Testing Methods and Tools

Date Code 20110408 Instruction Manual SEL-551 Relay
Section 8
Testing and Troubleshooting
Overview
The Acceptance Testing on page 8.4, Commissioning Testing on page 8.14,
and Maintenance Testing on page 8.15 should be used for determining and
establishing test routines for the SEL-551 Relay. Included are discussions on
testing philosophies, methods, and tools. Example test procedures are shown
for the overcurrent elements, differential elements, and metering. Relay
troubleshooting procedures are shown at the end of the section.
Protective relay testing can be divided into three categories:
➤ acceptance
➤ commissioning
➤ maintenance
The categories are differentiated by when they take place in the life cycle of
the relay, as well as in the test complexity.
The paragraphs below describe when each type of test is performed, the goals
of testing at that time, and the relay functions that you need to test at each
point. This information is intended as a guideline for testing SEL relays.
Testing Methods and Tools
Test Features
Provided by the Relay
The following features assist you during relay testing:
Feature Description
METER Command The METER command shows the currents presented to the relay
in primary values. Compare these quantities against other devices
of known accuracy.
EVENT Command The relay generates an event report in response to faults or distur-
bances. Each report contains current information, relay element
states, and input/output contact information. If you question the
relay response or your test method, use the EVENT command to
display detailed information.
TARGET
Command
Use the TARGET n command to view the state of relay control
inputs, relay outputs, and relay elements individually during a test.
SER Command Use the Sequential Event Recorder for timing tests by setting the
SER trigger settings (SER1, SER2, or SER3) to trigger for specific
elements asserting or deasserting. View the SER with the SER
command.
Programmable
Outputs
Programmable outputs allow you to isolate individual relay ele-
ments. Refer to the SET command.