Sel 751A - Figure 5.21 Breaker Monitor Accumulates 25 Percent Wear

5.21
Date Code 20100129 Instruction Manual SEL-751A Relay
Metering and Monitoring
Breaker Monitor
10 Percent to 25 Percent Breaker Wear
Refer to Figure 5.21. The current value changes from 7.0 kA to 2.5 kA. 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.
Figure 5.21 Breaker Monitor Accumulates 25 Percent Wear
10,000
100%
10%
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
25%