11.4
SEL-751 Relay Instruction Manual Date Code 20170927
Testing and Troubleshooting
Commissioning Tests
Step 4. Apply ac or dc control voltage to the relay.
After the relay is energized, the front-panel green ENABLED LED
should illuminate.
Step 5. Use the appropriate serial cable (SEL Cable C234A or
equivalent) to connect a PC to the relay.
Step 6. Start the PC terminal emulation software and establish
communication with the relay.
Refer to Section 7: Communications for more information on
serial port communications.
Step 7. Set the correct relay time and date by using either the front-
panel or serial port commands.
Step 8. Using the SET, SET P, SET G, SET L, and SET R serial port
commands, enter the relay settings from the settings sheets for
your application.
Step 9. If you are connecting an external SEL-2600 RTD Module,
perform the following substeps; otherwise, continue with the next
step.
a. Connect the fiber-optic cable to the RTD Module fiber-
optic output.
b. Plug the relay end of the fiber-optic cable into the relay
fiber-optic input (Port 2).
Step 10. Verify the relay ac connections.
Step 11. Connect the ac test source current or voltage to the appropriate
relay terminals.
NOTE: Make sure the current
transformer secondary windings are
shorted before they are disconnected
from the relay.
a. Disconnect the current transformer and voltage
transformer (if present) secondaries from the relay prior
to applying test source quantities.
b. If you set the relay to accept phase-to-ground voltages
(DELTA_Y := WYE), set the current and/or voltage
phase angles as shown in Figure 11.2.
c. If you set the relay to accept delta voltages
(DELTA_Y := DELTA), set the current and/or voltage
phase angles as shown in Figure 11.3.
Before working on a CT circuit, first
apply a short to the secondary
winding of the CT.
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