11.3
Date Code 20170927 Instruction Manual SEL-751 Relay
Testing and Troubleshooting
Commissioning Tests
Step 8. Locate connector J4 and connect low-level signal connector
(e.g., ribbon cable connector of SEL-RTS Test System).
Step 9. Insert the board back into Slot E. Refer to the SEL-RTS
Instruction Manual for additional detail.
When simulating a delta PT connection, DELTA_Y := DELTA, with the low
level test interface referenced in Figure 11.1, apply the following signals:
➤ Apply low-level test signal VAB to Pin VA.
➤ Apply low-level test signal –VBC (equivalent to VCB) to Pin
VC.
➤ Do not apply any signal to pin VB.
Commissioning Tests
SEL performs a complete functional check and calibration of each SEL-751
Relay before it is shipped. This helps to ensure that you receive a relay that
operates correctly and accurately. Commissioning tests confirm that the relay
is properly connected including the control signal inputs and outputs.
The following connection tests help you enter settings into the SEL-751 and
verify that the relay is properly connected. Brief functional tests ensure that
the relay settings are correct. It is unnecessary to test every element, timer, and
function in these tests. Modify the procedure as necessary to conform to your
standard practices. Use the procedure at initial relay installation; you should
not need to repeat it unless major changes are made to the relay electrical con-
nections.
Required Equipment
➤ The SEL-751, installed and connected according to your
protection design
➤ A PC with serial port, terminal emulation software, and serial
communications cable
➤ SEL-751 Settings Sheets with settings appropriate to your
application and protection design
➤ The ac and dc elementary schematics and wiring diagrams for
this relay installation
➤ A continuity tester
➤ A protective relay ac test source
➢ Minimum: single-phase voltage and current with phase
angle control
➢ Preferred: three-phase voltage and current with phase
angle control
Connection Tests
Step 1. Remove control voltage and ac signals from the SEL-751 by
opening the appropriate breaker(s) or removing fuses.
Step 2. Isolate the relay contact assigned to be the TRIP output.
Step 3. Verify correct ac and dc connections by performing point-to-
point continuity checks on the associated circuits.
NOTE: You can use the 14-pin
connectors of the SEL-RTS ribbon
cable C703. The connectors are not
keyed; make sure Pin 1 is connected to
the IA/VS channel on the 4 ACI/3 AVI
and 2 AVI/4 AFDI boards, respectively.
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