Siemens 6MD85 Manual page 1025

[LoCBWIxF, 1, en_US]
Figure 9-25
(1) Current-flow criterion fulfilled
(2) 20 ms prior value
Calculation of the Wear
If the ΣI x -method stage receives the logic release signal, the determined tripping current is used in the calcula-
tion of wear. The calculation results are then added to the existing statistic values of the ΣI
follows, with phase A as example.
[FoCBWIxA-301012-01.tif, 1, en_US]
Where:
x
q
m
The phase-selective ΣI
the specific application.
To simplify the interpretation of the sum of the tripping current powers, the values are set in relation to the
exponentiated rated normal current I
Circuit-Breaker Maintenance Warning
If the summated ΣI
generated.
SIPROTEC 5, High-Voltage Bay Controller, Manual
C53000-G5040-C015-9, Edition 11.2017
Logic of the Determination of the Tripping Current Value
Parameter exponent
No. of circuit-breaker switching cycle
Tripping/opening current of phase A to the power of x in the qth circuit-
breaker operation
Rated normal current to the power of x
Statistic value of current phase A calculated with the ∑I
Total number of switching cycles
x value is available as statistical value. You can reset or preset the statistics according to
of the circuit-breaker (see also Setting notes).
rated
x value of any phase is greater than the threshold, a phase-selective warning signal is
Measured Values, Energy Values, and Supervision of the Primary System
9.6 Circuit-Breaker Wear Monitoring
x method as
x method
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