8.5
Date Code 20080103 Instruction Manual SEL-351S Relay
Breaker Monitor, Metering, and Load Profile Functions
Breaker Monitor
Figure 8.2 SEL-351S Breaker Maintenance Curve for a 25 kV Circuit
Breaker
In Figure 8.2, note that the breaker maintenance curve levels off horizontally
above set point KASP1, COSP1. This is the close/open operation limit of the
circuit breaker (COSP1 = 10000), regardless of interrupted current value.
Also, note that the breaker maintenance curve falls vertically below set point
KASP3, COSP3. This is the maximum interrupted current limit of the circuit
breaker (KASP3 = 20.0 kA). If the interrupted current is greater than setting
KASP3, the interrupted current is accumulated as a current value equal to
setting KASP3.
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
To Next Page
