8.5
Date Code 20060320 Instruction Manual SEL-311C Relay
Breaker Monitor and Metering Functions
Breaker Monitor
Figure 8.2 SEL-311C Breaker Maintenance Curve for an Example Circuit Breaker
In Figure 8.2, note that the breaker maintenance curve levels off horizontally
to the left of set point KASP1, COSP1. This is the close/open operation limit
of the circuit breaker (COSP1 = 10000), regardless of interrupted current
value.
10,000
100%
1000
2
3
4
5
6
7
8
9
100
2
3
4
5
6
7
8
9
10
2
3
4
5
6
7
8
9
123456789
50
40
30
20
10
.5
Number of Close/Open Operations
kA Interrupted per Operation
KASP1 = 1.2
COSP1 = 10000
KASP2 = 8.0
COSP2 = 150
KASP3 = 20.0
COSP3 = 12
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