ABB REB670 Applications Manual page 424

Section 14
Monitoring
418
• 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 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
1MRK 505 337-UUS -
y
. The factor "y"
Application manual