11.6
SEL-751 Relay Instruction Manual Date Code 20170927
Testing and Troubleshooting
Commissioning Tests
Step 15. If you are using a core-balance current transformer, apply a
single-phase current to the IN terminals. Do not apply voltage.
Step 16. Verify that the relay is measuring the magnitude and phase
angle correctly.
The expected magnitude is (applied current) •
(CTRN).
Step 17. Verify control input connections. Using the front-panel
MAIN > Targets > Row 17 function, check the control input
status in the relay.
As you apply rated voltage to each input, the position in Row
17 corresponding to that input should change from zero (0) to
one (1).
Step 18. Verify output contact operation:
Program each of the output contacts you want to test to
logical 1. This causes the output contact to close. For example,
setting OUT101 = 1 causes the output OUT101 contact to close.
Make sure that each contact closure does what you want it to do
in the annunciation, control, or trip circuit associated with that
contact closure.
Step 19. Perform any desired protection element tests. Perform only
enough tests to prove that the relay operates as intended;
exhaustive element performance testing is not necessary for
commissioning.
Step 20. Connect the relay for tripping duty.
Step 21. Verify that any settings changed during the tests performed in
Step 18 and Step 19 are changed back to the correct values for
your application.
Step 22. Use the serial port commands in Table 11.2 to clear the relay
data buffers and prepare the relay for operation.
This prevents data generated during commissioning testing
from being confused with operational data collected later.
Step 23. When it is safe to do so, energize the feeder.
Step 24. Verify the following ac quantities by using the front-panel
METER > Fundamental or serial port METER command.
➢ Phase current magnitudes should be nearly equal.
➢ Phase current angles should be balanced, have proper
phase rotation, and have the appropriate phase
relationship to the phase voltages.
Table 11.2 Serial Port Commands That Clear Relay Data Buffers
Serial Port Command Ta s k Performed
LDP C Clears Load Profile Data
SER R Resets Sequential Events Record buffer
SUM R Resets Event Report and Summary Command buffers
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