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1MRK 505 370-UEN D
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 operating current. The remaining
life of the CB would become (10000 – 200) = 9800 operations at the rated operating
current after one operation at 50 kA.
Accumulated energy
Monitoring the contact erosion and interrupter wear has a direct influence on the required
maintenance frequency. Therefore, it is necessary to accurately estimate the erosion of the
contacts and condition of interrupters using cumulative summation of I
depends on the type of circuit breaker. The energy values were accumulated using the current
value and exponent factor for CB contact opening duration. When the next CB opening
operation is started, the energy is accumulated from the previous value. The accumulated
energy value can be reset to initial accumulation energy value by using the Reset accumulating
energy input, RSTIPOW.
Circuit breaker operation cycles
Routine breaker maintenance like lubricating breaker mechanism is based on the number of
operations. A suitable threshold setting helps in preventive maintenance. This can also be used
to indicate the requirement for oil sampling for dielectric testing in case of an oil circuit
breaker.
Circuit breaker operation monitoring
By monitoring the activity of the number of operations, it is possible to calculate the number
of days the breaker has been inactive. Long periods of inactivity degrade the reliability for the
protection system.
Circuit breaker spring charge monitoring
For normal circuit breaker operation, the circuit breaker spring should be charged within a
specified time. Detecting a long spring charging time indicates the time for circuit breaker
maintenance. The last value of the spring charging time can be given as a service value.
Circuit breaker gas pressure indication
For proper arc extinction by the compressed gas in the circuit breaker, the pressure of the gas
must be adequate. Binary input available from the pressure sensor is based on the pressure
levels inside the arc chamber. When the pressure becomes too low compared to the required
value, the circuit breaker operation is blocked.
14.4.3
Setting guidelines
The breaker monitoring function is used to monitor different parameters of the circuit
breaker. The breaker requires maintenance when the number of operations has reached a
predefined value. For proper functioning of the circuit breaker, it is also essential to monitor
the circuit breaker operation, spring charge indication or breaker wear, travel time, number of
operation cycles and accumulated energy during arc extinction.
Busbar protection REB670
Application manual
Section 14
Monitoring
y
. The factor "y"
GUID-AB93AD9B-E6F8-4F1A-B353-AA1008C15679 v3
367
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