ABB REC650 Applications Manual page 314

Section 12
Monitoring
308
Breaker contact travel time
High travelling times indicate the need for maintenance of the circuit breaker mechanism.
Therefore, detecting excessive travelling 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 close 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 like the 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
1MRK 511 286-UUS A
y
t where the factor y is known
Application manual