U.2.12
SEL-421/SEL-421-1 Relay
User’s Guide
Date Code 20020501
Installation
Plug-In Boards
Plug-In Boards
The SEL-421 Relay is available in many input/output configuration options.
The relay base model is a 3U chassis with Standard I/O and screw terminal
connector connections (see
). Other ordering options
include versions of the relay in larger enclosures (4U or 5U) with all, partial,
or no extra I/O boards installed.
NOTE:
Ordering the 4U and 5U relay
with partial or no extra I/O allows for
future system expansion and future
use of additional relay features.
Also available for the SEL-421 Relay is a plug-in communications card. The
optional SEL-2701 Ethernet Processor communications card allows you to
use TCP/IP, FTP, Telnet, and UCA2 applications on an Ethernet network.
I/O Interface Boards
You can choose among three input/output interface boards for the I/O slots of
the 4U and 5U chassis. These I/O interface boards are in addition to the main
board I/O described in
Shared Configuration Attributes on page 2.2
. The I/O
interface boards are INT1, INT5, and INT6.
and
show
the rear screw terminal connectors associated with these interface boards.
Figure 2.10
INT1 or INT6 I/O Interface Board.
Figure 2.11
INT5 I/O Interface Board.
The I/O interface boards carry jumpers that identify the board location. See
for more information on I/O board jumpers.
I/O Interface Board Inputs
All optional I/O interface boards have eight independent control inputs. All
independent inputs are isolated from other inputs. These high-isolation control
inputs are polarity-sensitive, ground-isolated circuits. You cannot damage
these inputs with a reverse polarity connection; though, the relay will not
detect input changes with a reverse-polarity input.
is a comparison of the I/O board input capacities; the table also
shows the I/O inputs on the main board. See
Control Inputs on page U.1.11 in
for complete control input specifications.
.
Table 2.1
I/O Interface Boards Control Inputs
Board Number
Independent Contact Pairs
Common Contact Pairs
INT1
8
INT5
8
INT6
8
Main Board
5
2
Summary of Contents for SEL-421
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