Schweitzer Engineering Laboratories SEL-351 - Page 308

8-2 Breaker Monitor, Metering, and Load Profile Functions Date Code 20001006
SEL-351 Instruction Manual
Table 8.1: Breaker Maintenance Information
for a 25 kV Circuit Breaker
Current
Interruption
Level (kA)
Permissible Number
of Close/Open
Operations
*
0.00 - 1.20 10,000
2.00 3,700
3.00 1,500
5.00 400
8.00 150
10.00 85
20.00 12
*
The action of a circuit breaker closing and then later opening is counted as one
close/open operation.
The breaker maintenance information in Table 8.1 is plotted in Figure 8.1.
Connect the plotted points in Figure 8.1 for a breaker maintenance curve. To estimate this breaker
maintenance curve in the SEL-351 Relay breaker monitor, three set points are entered:
Set Point 1 maximum number of close/open operations with corresponding current
interruption level.
Set Point 2 number of close/open operations that correspond to some midpoint current
interruption level.
Set Point 3 number of close/open operations that correspond to the maximum current
interruption level.
These three points are entered with the settings in Table 8.2.
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