8.7
Date Code 20060320
Instruction Manual
SEL-311C Relay
Breaker Monitor and Metering Functions
Breaker Monitor
0 Percent to 10 Percent Breaker Wear
in which 7.0 kA is interrupted 20 times, pushing the
breaker maintenance curve from the 0 percent wear level to the 10 percent
wear level.
Compare the 100 percent and 10 percent curves and note that for a given
current value, the 10 percent curve has only 1/10 of the close/open operations
of the 100 percent curve.
10 Percent to 25 Percent Breaker Wear
. The current value changes from 7.0 kA to 2.5 kA. The
value 2.5 kA is interrupted 290 times (290 close/open operations = 480 – 190),
pushing the breaker maintenance curve from the 10 percent wear level to the
25 percent wear level.
Compare the 100 percent and 25 percent curves and note that for a given
current value, the 25 percent curve has only 1/4 of the close/open operations
of the 100 percent curve.
25 Percent to 50 Percent Breaker Wear
. The current value changes from 2.5 kA to 12.0 kA, and
12.0 kA is interrupted 11 times (11 close/open operations = 24 – 13), pushing
the breaker maintenance curve from the 25 percent wear level to the
50 percent wear level.
Compare the 100 percent and 50 percent curves and note that for a given
current value, the 50 percent curve has only 1/2 of the close/open operations
of the 100 percent curve.
50 Percent to 100 Percent Breaker Wear
. The current value changes from 12.0 kA to 1.5 kA, and
1.5 kA is interrupted 3000 times (3000 close/open operations = 6000 – 3000),
pushing the breaker maintenance curve from the 50 percent wear level to the
100 percent wear level.
When the breaker maintenance curve reaches 100 percent for a particular
phase, the percentage wear remains at 100 percent (even if additional current
is interrupted), until reset by the
BRE R
command (see
Monitor Information on page 8.12
). Current and trip counts continue to be
accumulated, until reset by the
BRE R
command.
Additionally, logic outputs assert for alarm or other control applications—see
the following discussion.
Summary of Contents for SEL-311C
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