Schweitzer Engineering Laboratories, Inc. SEL-451 Data Sheet
7
Multifunction Reclosing With
Flexible Applications
The SEL-451 includes three-pole trip and reclose func-
tions, for either one or two breakers (Figure 4). Synchro-
nism check is included for breaker control.
Synchronizing and polarizing voltage inputs are fully
programmable with Dead Line/Dead Bus closing logic as
well as zero-closing-angle logic to minimize system
stress upon reclosing. Program as many as four reclose
attempts. Select Leader and Follower breakers directly,
or use a SEL
OGIC control equation to determine reclos-
ing order based on system conditions.
Two-Breaker Control
The SEL-451 contains analog voltage inputs for multiple
sources and control inputs to indicate both breaker and
disconnect position, as well as the logic required to pro-
vide full control for two breakers. This includes separate
monitoring functions as well as separate elements for
tripping and closing the two breakers to allow for
leader/follower operation or other desired control
schemes. All analog values are monitored on a per-
breaker basis to allow station control access to complete
information for individual components of the system.
Backup Protection
Add reliability and dependability by providing indepen-
dent backup protection without increasing relay count.
Use each SEL-451 to provide primary directional over-
current protection with backup nondirectional overcur-
rent protection on the adjacent feeder. For additional
flexibility, use the available I/O or M
IRRORED BITS to
switch protection upon loss of one relay.
Bay Control
The SEL-451 Bay Control provides dynamic bay one-
line diagrams on the front-panel screen with disconnect
and breaker control capabilities for numerous predefined
user-selectable bay types. Additional user-selectable bay
types are available via a QuickSet interface that can be
downloaded at selinc.com. The bay control is equipped
to control as many as 10 disconnects and two breakers,
depending on the one-line diagram selected. Certain one-
line diagrams provide status for as many as three break-
ers and ten disconnect switches. Operate disconnects and
breakers with ASCII commands, SEL
OGIC control equa-
tions, Fast Operate Messages, and from the one-line dia-
gram. The one-line diagram includes user-configurable
apparatus labels and as many as 24 user-definable Ana-
log Quantities.
One-Line Bay Diagrams
The SEL-451 offers a variety of preconfigured one-line
diagrams for common bus configurations. Once a one-
line diagram is selected, the user has the ability to cus-
tomize the names for all of the breakers, disconnect
switches, and buses. Most one-line diagrams contain
analog display points. These display points can be set to
any of the available analog quantities with labels, units,
and scaling. These values are updated real-time along
with the breakers and switch position to give instant sta-
tus and complete control of a bay. The diagrams below
demonstrate some of the preconfigured bay arrange-
ments available in the SEL-451.
Figure 4 Two-Breaker Reclosing With Synchronism Check
52-1
52-2
Line
Bus 2
Bus 1
79
25
Figure 5 Using Two Cross-Connected SEL-451-5 Relays
to Provide Primary and Backup Protection for Two
Feeders
SEL-451 SEL-451
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