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
395.
N
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m
b
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r
o
f
m
a
k
e
-
b
r
e
a
k
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(
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Interrupted current (kA)
P1
P2
100000
50000
20000
10000
2000
5000
1000
100
200
500
10
20
50
0.1 0.2 0.5 1 2 5 10 20 50 100
IEC12000623_1_en.vsd
IEC12000623 V1 EN
Figure 395: 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
Section 18 1MRK 506 369-UUS -
Monitoring
832 Line distance protection REL670 2.2 ANSI
Application manual
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