10.10
SEL-751A Relay Instruction Manual Date Code 20100129
Testing and Troubleshooting
Commissioning Tests
word bits AFSnDIAG picks up), the AFALARM relay word bit picks up and
gives a WARNING on the relay front panel and asserts the ALARM output
contact.
Command AFT (Arc-Flash test)
The relay performs the arc-flash self-test periodically as discussed above.
Additionally, by using the serial port ASCII command AFT, the relay
performs the self-test on demand in all four channels and reports the status of
each channel. This same test is also available from the Control Window in the
ACSELERATOR QuickSet
®
SEL-5030 Software and the relay front panel
STATUS sub-menu. Refer to Figure 7.16 for the AFT command response
example. The response shows the light measurements in percent of full scale
and the PASS/FAIL status. The PASS indication means the channel is healthy
and ready to detect an arc-flash event. The FAIL indication means the channel
in question is not healthy and needs repair and testing when a convenient
outage is available for maintenance.
Testing the Arc-Flash Time-Over-Light Elements TOL1 to TOL4
Test the TOL elements once the relay has been set, as described in Section 4:
Protection and Logic Functions for the arc-flash protection elements. The
TOL1 to TOL4 relay word bits should be added to the SER (Sequence of
events report) settings so that the relay can capture the TOL element assertion
and dropout. Apply a bright light source near the light sensor (POINT or
BARE-FIBER type) in the switchgear cabinet and note that the appropriate
TOL element relay word bit picks up and drops out as expected.
The arc-flash test can also be captured as a CEV event report by triggering the
event report with the TOLn relay word bit. The CEV R (raw data) event report
should be viewed using the
ACSELERATOR
®
Analytic Assistant SEL-5601
Software. The % light intensity analog quantity can be viewed together with
the TOLn relay word bit to verify the correct operation.
Testing the Arc-Flash Overcurrent Elements 50PAF and 50NAF
These current elements are similar to the 50P and 50N elements, except they
use 'raw' current input samples and act instantaneously to achieve fast
response. These elements can be tested just like the 50P and 50N elements as
mentioned in the commissioning tests described above. The CEV R report can
be used as above to analyze the event.
Testing the Complete Arc-Flash Protection Sytem
It is not necessary to verify the complete protection subsystem as the relay is
tested at the factory before shipping. If a synchronized light and current pulse
test source is available to simulate an arc, it can be used to exercise the arc-
flash protection TOLn elements together with the 50PAF or the 50NAF
elements. If the relay has been set for the arc-flash protection including the
tripping logic, the test could exercise the breaker tripping (unenergized state).
The total event can be captured with appropriate event report trigger settings
and the CEV R (raw data) report can be viewed and analyzed using
ACSELERATOR Analytic Assistant. The CEV R report will show the analog
currents and light channels together with the relay word bits so that the
response can be analyzed and qualified. Figure 10.6 shows an example event
report for a simulated arc-flash incident.
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