8.4
SEL-351A Relay Instruction Manual Date Code 20080213
Breaker Monitor and Metering
Breaker Monitor
Breaker Monitor
Setting Example
Setting notes:
➤ COSP1 must be set greater than COSP2.
➤ COSP2 must be set greater than or equal to COSP3.
➤ KASP1 must be set less than KASP2.
➤ If COSP2 is set the same as COSP3, then KASP2 must be set
the same as KASP3.
➤ KASP3 must be set at least 5 times (but no more than 100
times) the KASP1 setting value.
The following settings are made from the breaker maintenance information in
Table 8.1 and Figure 8.1:
COSP1 = 10000
COSP2 = 150
COSP3 = 12
KASP1 = 1.20
KASP2 = 8.00
KASP3 = 20.00
Figure 8.2 shows the resultant breaker maintenance curve.
Breaker Maintenance Curve Details
In Figure 8.2, note that set points KASP1, COSP1 and KASP3, COSP3 are set
with breaker maintenance information from the two extremes in Tabl e 8.1 and
Figure 8.1.
In this example, set point KASP2, COSP2 happens to be from an in-between
breaker maintenance point in the breaker maintenance information in
Table 8.1 and Figure 8.1, but it does not have to be. Set point KASP2, COSP2
should be set to provide the best “curve-fit” with the plotted breaker
maintenance points in Figure 8.1.
Each phase (A, B, and C) has its own breaker maintenance curve (like that in
Figure 8.2), because the separate circuit breaker interrupting contacts for
phases A, B, and C do not necessarily interrupt the same magnitude current
(depending on fault type and loading).
Table 8.2 Breaker Monitor Settings and Settings Ranges
Setting Definition Range
COSP1 Close/Open
set point 1—maximum
0–65000 close/open operations
COSP2 Close/Open set point 2—middle 0–65000 close/open operations
COSP3 Close/Open set point 3—minimum 0–65000 close/open operations
KASP1 kA Interrupted
set point 1—minimum
0.00–999.00 kA in 0.01 kA steps
KASP2 kA Interrupted set point 2—middle 0.00–999.00 kA in 0.01 kA steps
KASP3 kA Interrupted
set point 3—maximum
0.00–999.00 kA in 0.01 kA steps
BKMON SEL
OGIC
®
control equation
breaker monitor initiation setting
Relay Word bits referenced in Ta ble 9.5
Courtesy of NationalSwitchgear.com
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