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Schweitzer Engineering Laboratories, Inc. SEL-451 Data Sheet
15
Breaker Monitor Feature Allows
for Wear-Based Breaker
Maintenance Scheduling
Circuit breakers experience mechanical and electrical
wear at each operation. Effective scheduling of breaker
maintenance takes into account the manufacturer’s pub-
lished data of contact wear versus interruption levels and
operation count. The SEL-451 dual breaker monitor fea-
ture compares the breaker manufacturer’s published data
to the integrated actual interrupted current and number of
operations.
➤
Every time the breaker trips, the relay integrates
interrupted current. When the result of this
integration exceeds the threshold set by the breaker
wear curve (
Figure 21 ), the bay can alarm via an
output contact or the optional front-panel display.
With this information, you can schedule breaker
maintenance in a timely, economical fashion.
➤
The relay monitors last and average mechanical
and electrical interruption time. You can easily
determine if operating time is increasing beyond
reasonable tolerance to schedule proactive breaker
maintenance. You can activate an alarm point if
operation time goes beyond a preset value.
➤
Breaker motor run time and breaker inactivity are
also monitored.
Automation
Time-Domain Link (TiDL) Technology
The SEL-451 supports remote data acquisition through
use of an SEL Axion with a technology known as TiDL.
The Axion provides remote analog and digital data over
an IEC 61158 EtherCAT TiDL network. This technology
provides very low and deterministic 1.5 ms latency over
a point-to-point architecture. The SEL-451 can receive as
many as eight fiber links from as many as eight Axion
remote data acquisition nodes.
The relay supports a number of fixed topologies. The
relay maps the voltage and current inputs from the Axion
to existing analog quantities in the SEL-451 based on the
connected topology. This limits the number of settings
and makes converting an existing system to TiDL easy.
Figure 22 show sample TiDL topologies. The SEL-451-5
Instruction Manual shows all supported topologies.
Synchrophasors
Voltages (Primary Magnitude, Angle)
V
A,B,C
(Y), V
A,B,C
(Z)
Primary phase quantities (kV) for each of the six voltage sources available.
Currents (Primary Magnitude, Angle)
I
A,B,C
(W), I
A,B,C
(X)
Primary phase quantities (A) for each of the six current sources available.
Frequency
FREQ
dF/dT
Frequency (Hz) as measured by frequency source potential inputs.
Rate-of-change of frequency (Hz/s).
Table 3 Metering Capabilities (Sheet 2 of 2)
Capabilities Description
Figure 21 Breaker Contact Wear Curve and Settings
kA Interrupted
(Set Point 1)
(Set Point 2)
(Set Point 3)
Breaker Manufacturer's
Maintenance Curve
Close to Open Operations