U.2.8
SEL-421/SEL-421-1 Relay
User’s Guide
Date Code 20020501
Installation
Shared Configuration Attributes
Figure 2.6
Hybrid Control Output Connection.
See
Section 1: Introduction and Specifications in the User’s Guide
, for
complete Hybrid control output specifications.
Fast Hybrid (Fast High-Current-Interrupting) Control Outputs
NOTE:
You can use ac or dc circuits
with Fast Hybrid (fast high-current-
interrupting) outputs.
In addition to the Standard control outputs and the Hybrid control outputs, I/O
interface board INT5 offers Fast Hybrid (fast high-current-interrupting)
control outputs. These control outputs have a resistive load pickup time of 10
m
s (microseconds), which is much faster than the 6 ms pickup time of the
Standard and Hybrid control outputs. The Fast Hybrid control outputs drop
out at a maximum time of 8 ms. The maximum voltage rating is 250 Vac/330
Vdc. See
Control Outputs on page U.1.11 in the User’s Guide
, for complete
Fast Hybrid control output specifications.
shows a representative
connection for a Form A Fast Hybrid control output on the INT5 I/O interface
terminals.
Figure 2.7
Fast Hybrid Control Output Connection.
Short transient inrush current can flow at the closing of an external switch in
series with open Fast Hybrid contacts. This transient will not energize the
circuits in typical relay-coil control applications (trip coils and close coils),
and standard auxiliary relays will not pick up. However, an extremely
sensitive digital input or light-duty, high-speed auxiliary relay can pick up for
this condition. This false pick-up transient occurs when the capacitance of the
Fast Hybrid output circuitry charges (creating a momentary short circuit that a
fast, sensitive device sees as a contact closure). A third terminal (03 in
) provides an internal path for precharging the Fast Hybrid output
circuit capacitance when the circuit is open.
OUT01
+
O1
O2
01
03
02
OUT04
Summary of Contents for SEL-421
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