ABB RER670 Applications Manual page 398

Section 15
Monitoring
392
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Interrupted current (kA)
IEC12000623 V1 EN-US
Figure 162: 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 remaining life of the CB would be (10000 – 10) = 9989
at the rated operating current after one operation at 10 kA.
• Breaker interrupts at and above rated fault current, that is, 50 kA, one
operation at 50 kA is equivalent to 10000/50 = 200 operations at the rated
P1
2 5 10 20 50
IEC12000623_1_en.vsd
1MRK 506 375-UEN A
P2
100
Railway application RER670 2.2 IEC
Application manual