ABB REB670 Series, Руководство по применению

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Remaining life of circuit breaker
Every time the breaker operates, the circuit breaker life reduces due to wear. The wear in a
breaker depends on the interrupted current. For breaker maintenance or replacement at the
right time, the remaining life of the breaker must be estimated. The remaining life of a breaker
can be estimated using the maintenance curve provided by the circuit breaker manufacturer.
Circuit breaker manufacturers provide the number of make-break operations possible at
various interrupted currents. An example is shown in figure 199 .
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Interrupted current (kA)
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IEC12000623_1_en.vsd
IEC12000623 V1 EN-US
Figure 199: An example for estimating the remaining life of a circuit breaker
Calculation for estimating the remaining life
The graph shows that there are 10000 possible operations at the rated operating current and
900 operations at 10 kA and 50 operations at rated fault current. Therefore, if the interrupted
current is 10 kA, one operation is equivalent to 10000/900 = 11 operations at the rated current.
It is assumed that prior to tripping, the remaining life of a breaker is 10000 operations.
Remaining life calculation for three different interrupted current conditions is explained below.
• Breaker interrupts at and below the rated operating current, that is, 2 kA, the remaining
life of the CB is decreased by 1 operation and therefore, 9999 operations remaining at the
rated operating current.
• Breaker interrupts between rated operating current and rated fault current, that is, 10 kA,
one operation at 10kA is equivalent to 10000/900 = 11 operations at the rated current. The
Section 14 1MRK 505 370-UEN D
Monitoring
366 Busbar protection REB670
Application manual