10.4
SEL-749M Relay Instruction Manual Date Code 20080918
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, and SET L 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,
follow the substeps below; otherwise continue with the next
step.
a. Connect the fiber-optic cable to the module fiber-optic
output.
b. Plug the relay end of the fiber-optic cable into the relay
fiber-optic input.
Step 10. Verify the relay ac connections.
Step 11. Connect the ac test source current or voltage to the appropriate
relay terminals.
Disconnect the current transformer and voltage transformer (if
present) secondaries from the relay prior to applying test source
quantities.
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 10.2.
If you set the relay to accept delta voltages (DELTA_Y :=
Delta), set the current and/or voltage phase angles as shown in
Figure 10.3.
Step 12. Apply rated current (1 A or 5 A).
Step 13. If the relay is equipped with voltage inputs, apply rated voltage
for your application.
Step 14. Use the front-panel
METER VALUES > INSTANTANEOUS METER
function or serial port METER command to verify that the
relay is measuring the magnitude and phase angle of both
voltage and current correctly, taking into account the relay PTR
and CTR1 settings and the fact that the quantities are displayed
in primary units.
Step 15. If you are using a core balance current transformer, apply a
single-phase current (A-Phase) to the IN terminals. Do not
apply voltage.
NOTE: Make sure the current
transformer secondary windings are
shorted before they are disconnected
from the relay.
Courtesy of NationalSwitchgear.com
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