ABB REL670 2.2 IEC, Applications Manual

Page: 786 / 908

• 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
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 18
1MRK 506 369-UEN B
Monitoring
780 Line distance protection REL670 2.2 IEC
Application manual