U.2.42
SEL-421/SEL-421-1 Relay
User’s Guide
Date Code 20020501
Installation
Connection
The INT5 I/O interface board features high-speed operation capability using
Fast Hybrid control outputs. To limit the false pickup indications with digital
inputs and light duty high-speed auxiliary relays, precharging resistors are
available on the screw terminal connector for each pair of control output
contacts. See
Fast Hybrid (Fast High-Current-Interrupting) Control Outputs
for further information, and
for resistor connection details.
Alarm Output
The SEL-421 Relay monitors internal processes and hardware in continual
self-tests. If the relay senses an out-of-tolerance condition, the relay declares a
Status Warning or a Status Failure. The relay signals a Status Warning by
pulsing the HALARM Relay Word bit (hardware alarm) to a logical 1 for five
seconds. For a Status Failure, the relay latches the HALARM Relay Word bit
at logical 1.
To provide remote alarm status indication, connect the ‘b’ contact of OUT108
to your control system remote alarm input.
shows the
configuration of the ‘a’ and ‘b’ contacts of control output OUT108.
Figure 2.29
Control Output OUT108.
Program OUT108 to respond to NOT HALARM by entering the following
SEL
OGIC®
control equation with a communications terminal, with the
AC
SEL
ERATOR
software, or by using the front-panel LCD and navigation
pushbuttons:
OUT108 :=
NOT HALARM
When the relay is operating normally, the NOT HALARM signal is at logical
1 and the ‘b’ contacts of control output OUT108 are open. When a Status
Warning condition occurs, the relay pulses the NOT HALARM signal to
logical 0 and the ‘b’ contacts of OUT108 close momentarily to indicate an
alarm condition. For a Status Failure, the relay disables all control outputs and
the OUT108 ‘b’ contacts close to trigger an alarm. Also, when relay power is
off, the OUT108 ‘b’ contacts close to generate a power-off alarm. See
Self-Tests on page U.6.37 in the User’s Guide
for information on relay self-
tests.
N/O
N/C
C
OUT108
OUT108
a
b
(connect alarm here)
Summary of Contents for SEL-421
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