2.9
Date Code 20171021 Instruction Manual SEL-421 Relay
Installation
Shared Configuration Attributes
mechanical contact to interrupt (break) highly inductive dc currents. The contacts
can carry continuous current, while eliminating the need for heat sinking and pro-
viding security against voltage transients.
With any hybrid output, break time varies according to the circuit inductive/resis-
tive (L/R) ratio. As the L/R ratio increases, the time needed to interrupt the circuit
fully increases also. The reason for this increased interruption delay is that circuit
current continues to flow through the output MOV after the output deasserts,
until all of the inductive energy dissipates. Maximum dropout (break) time is 6
ms with a resistive load, the same as for the standard control outputs. The other
ratings of these control outputs are similar to the standard control outputs, except
that the hybrid outputs can break current as great as 10 A. Hybrid contact outputs
have a maximum voltage rating of 330 Vdc.
The maximum pickup time for the hybrid control outputs is 6 ms. Figure 2.5
shows a representative connection for a Form A hybrid control output on the
main board I/O terminals.
See Section 1: Introduction and Specifications, for complete hybrid control out-
put specifications.
High-Speed, High-Current Interrupting Control Outputs
NOTE: You can use ac or dc circuits
with high-speed, high-current
interrupting outputs.
In addition to the standard control outputs and the hybrid control outputs, the
INT4, INT5, and INT8 I/O interface boards offer high-speed, high-current inter-
rupting control outputs. These control outputs have a resistive load pickup time
of 10 s, which is much faster than the 6 ms pickup time of the standard and
hybrid control outputs. The high-speed, high-current interrupting 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 1.14, for complete high-speed, high-
current interrupting control output specifications.
Figure 2.6 shows a representative connection for a Form A high-speed, high-cur-
rent interrupting control output on the INT5 (INT8) I/O interface terminals.
Figure 2.5 Hybrid Control Output Connection
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