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10.27
Date Code 20171006
Instruction Manual
SEL-400 Series Relays
Testing, Troubleshooting, and Maintenance
Maintenance
c. Apply firm pressure to fully seat the I/O interface board.
If you encounter resistance, STOP and withdraw the board.
Inspect the drawout tray edge guide slots for damage.
If you see no damage, take all of the precautions outlined above
and try again to insert the board.
Step 11. Confirm screw-terminal connector keying.
a. Inspect the screw-terminal connector receptacles on the rear of
the I/O interface board.
shows the I/O board section without terminal
blocks. The yellow dividers are the connector keying for each
terminal block.
b. Refer to
for the corresponding key positions inside
the receptacle.
Figure 10.16
Screw-Terminal Connector Receptacles
Figure 10.17
Screw-Terminal Connector Keying
Key
A B C
2
1
3
C
A B
B
2
1
3
A
C
1 2 3
200-Addresses
Row B
A B C
1 2 3
A B C
1 2 3
100-Addresses
Row A
D E F
1 2 3
D E F
1 2 3
E
D
F
1 2 3
500-Addresses
Row E
D E F
1 2 3
D E F
1 2 3
E
D
F
1 2 3
400-Addresses
Row D
Insert Key
P/N 090-2915
(One Pair for Each
Screw-Terminal Connector)
A B C
2
1
3
C
A B
B
1 2 3
A
C
1 2 3
300-Addresses
Row C
Summary of Contents for SEL-421-4
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