
2
The SEL-751 offers flexibility in tailoring I/O to your specific application. The SEL-751 has six rear-panel slots, labeled
as Slots A, B, C, D, E, and Z. Slots A, B, and Zare base unit slots, each associated with a specific function. Optional
digital/analog I/O cards are available for the SEL-751 in Slots C, D, and E. Optional communications cards are available
only for Slot C; an RTD card is available only for Slot D; the 1 A/5 A/200 mA CT combinations for voltage/current or
current only cards are available only on Slot Z; and a voltage/arc-flash card is available for Slot E. The previous figure
and table show the slot allocations for the cards.
Because installations differ substantially, the SEL-751 offers a variety of card configurations that provide options for the
many diverse applications. Choose the combination of option cards most suited for your application from the selection.
Warnings
Card Installation for Slots C, D, E, and Z
Use the following procedure to install or replace any one of the cards into Slots C, D, E, or Zof the base unit:
1. Save the settings and event report data before installing the new card in the relay.
2. Remove the power supply voltage qfrom terminals A01 (+/H) and A02(–/N), and then remove the ground
wire from the green ground screw (GND).
3. Disconnect all the connection plugs.
4. Remove the eight (8) screws on the rear iand remove the rear cover.
5. Remove the plastic filler plate covering the slot associated with the card being installed.
6. Insert or replace the card in the correct slot.
For proper electromagnetic interference protection, make sure the contact fingers on the printed circuit
board are bent at approximately a 130° angle relative to the board.
7. Before reattaching the rear cover, check for and remove any foreign material that may remain inside the
SEL-751 case.
8. Carefully reattach the rear cover.
9. Reinstall the eight (8) screws that secure the rear cover to the case i.
10. Apply power supply voltage qto terminals A01 (+/H) and A02 (–/N), and reconnect the ground wire to the
green ground screw (GND).
11. If the card is in the proper slot, the front panel displays the following:
STATUS FAIL
X Card Failure
If you do not see this message and the ENABLED light is turned on, the card was inserted in the wrong slot.
Begin again at Step 2.
If you do see this message, then proceed to Step 12.
12. Press the ESC pushbutton.
13. Press the Down Arrow pushbutton until STATUS is highlighted.
Disconnect or de-energize all
external connections before
opening this device. Contact
with hazardous voltages and
currents inside this device
can cause electrical shock
resulting in injury or death.
Equipment components are sensitive to
electrostatic discharge (ESD).
Undetectable permanent damage can
result if you do not use proper ESD
procedures. Ground yourself, your work
surface, and this equipment before
removing any cover from this equipment.
To install an option card the relay must
be de-energized and then reenergized.
When reenergized, the relay will
reboot. Therefore, de-energize the
protected equipment before installing
the option card to prevent damage to
the equipment.
Have only qualified
personnel service this
equipment. If you are not
qualified to service this
equipment, you can injure
yourself or others, or cause
equipment damage.