ABB Relion 650 Series Applications Manual page 214

Section 12
Monitoring
Accumulation of I
Accumulation of I
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
A071114 V3 EN-US
Figure 102: Trip Curves for a typical 12 kV, 630 A, 16 kA vacuum interrupter
Nr
Ia
208
y
t
y
t calculates the accumulated energy ΣI
the number of closing-opening operations allowed for the circuit breaker
the current at the time of tripping of the circuit breaker
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y
t where the factor y is known as the
Busbar protection REB650
1MRK 505 287-UUS B
Application manual