ABB RELION 620 Series Technical Manual page 578

Section 6
Supervision functions
572
Circuit breaker operation monitoring
The purpose of the circuit breaker operation monitoring is to indicate that the circuit
breaker has not been operated for a long time. The function calculates the number of days
the circuit breaker has remained inactive, that is, has stayed in the same open or closed
state. There is also the possibility to set an initial inactive day.
Breaker contact travel time
High traveling times indicate the need for the maintenance of the circuit breaker
mechanism. Therefore, detecting excessive traveling time is needed. During the opening
cycle operation, the main contact starts opening. The auxiliary contact A opens, the
auxiliary contact B closes and the main contact reaches its opening position. During the
closing cycle, the first main contact starts closing. The auxiliary contact B opens, the
auxiliary contact A closes and the main contact reaches its closed position. The travel
times are calculated based on the state changes of the auxiliary contacts and the adding
correction factor to consider the time difference of the main contact's and the auxiliary
contact's position change.
Operation counter
Routine maintenance of the breaker, such as lubricating breaker mechanism, is generally
based on a number of operations. A suitable threshold setting to raise an alarm when the
number of operation cycle exceeds the set limit helps preventive maintenance. This can
also be used to indicate the requirement for oil sampling for dielectric testing in case of an
oil circuit breaker.
The change of state can be detected from the binary input of the auxiliary contact. There
is a possibility to set an initial value for the counter which can be used to initialize this
functionality after a period of operation or in case of refurbished primary equipment.
y
Accumulation of I t
y
Accumulation of I t calculates the accumulated energy ΣI
as the current exponent. The factor y depends on the type of the circuit breaker. For oil
circuit breakers, the factor y is normally 2. In case of a high-voltage system, the factor y
can be 1.4...1.5.
Remaining life of the breaker
Every time the breaker operates, the life of the circuit breaker reduces due to wearing. The
wearing in the breaker depends on the tripping current, and the remaining life of the
breaker is estimated from the circuit breaker trip curve provided by the manufacturer.
Example for estimating the remaining life of a circuit breaker
1MAC504801-IB E
y
t, where the factor y is known
620 series ANSI
Technical Manual