Sel 421 - For Details; Table 2.4 I;O Interface Boards Control Outputs; The SEL-421-0 and the SEL-421-1 Do Not Support Main Board B I;O and INT2, INT3, INT7, and INT8 I;O Interface Boards. See SEL-421; Versions and Supported Features on Page

U.2.15
Date Code 20090715 User’s Guide SEL-421 Relay
Installation
Plug-In Boards
NOTE: The SEL-421-0 and the
SEL-421-1 do not support Main Board B
I/O and INT2, INT3, INT7, and INT8 I/O
interface boards. See SEL-421
Versions and Supported Features on
page U.1.7 for details.
Installing Optional I/O Interface Boards
Perform the following steps to expand the capability of the SEL-421 with
additional I/O interface boards:
Step 1. Follow your company standard to remove the relay from
service.
Step 2. Disconnect power from the SEL-421.
Step 3. Retain the GND connection, if possible, and ground the
equipment to an ESD mat.
Step 4. Remove the communications cable connected to the front-panel
serial port, if applicable.
Step 5. Loosen the four front-panel screws (they remain attached to the
front panel), and remove the relay front panel.
Step 6. Remove the 34-pin ribbon cable from the front panel by
pushing the extraction ears away from the connector.
Step 7. Disconnect the power, the interface board, and the analog input
board cables from the main board.
Step 8. Confirm proper installation of address jumpers on the interface
board (see Jumpers on page U.2.18).
Step 9. Confirm drawout tray keying.
The relay chassis and the drawout trays for the 200-addresses
slot and the 300-addresses slot are keyed (see Figure 2.18).
The keys are two round plug-in/plug-out discs on the bottom of
the drawout tray.
The 200-addresses slot keys go to the left, and the 300-
addresses slot keys go to the right (when viewed from the top
and front of the drawout tray).
Table 2.4 I/O Interface Boards Control Outputs
Standard Fas t Hybri d
a
a
High-Speed/High-Current Interrupting.
Hybrid
b
b
High-Current Interrupting.
Board Number Form A Form C Form A Form A
INT1 13 2
INT2 13 2
INT3 4
INT4 2 6
INT5 8
INT6 2 13
INT7 2 13
INT8 8
Main Board A 2 3 3
Main Board B 2 3 3
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.
!
DANGER
Courtesy of NationalSwitchgear.com