ABB RELION REB670, Applications Manual

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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 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
y
.
The factor "y" 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.
Section 14
1MRK 505 370-UUS A
Monitoring
446 Busbar protection REB670 2.2 ANSI
Application manual