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Functions
2.23 Auxiliary Functions
SIPROTEC, 7SJ62/64, Manual
C53000-G1140-C207-2, Release date 01.2008
345
Note
Since a directional coefficient of m < -4 is technically irrelevant, but could theoretically be the result of incorrect
settings, it is limited to -4. If a coefficient is smaller than -4, the exponential function in the operating cycles
diagram is deactivated. The maximum number of operating cycles with
I
sc (
263
OP.CYCLES Isc
) is used
instead as the calculation result for the current number of operating cycles, see Figure 2-133.
Figure 2-133
Value limitation of directional coefficient
If the current criterion described in the Section „General“ grants the phase-selective logic release, the present
number of operating cycles is calculated based on the tripping currents determined when the CB operating time
on tripping has elapsed. They are set off against the remaining lifetime allowing the present statistic values to
be displayed and the evaluation to be started using the specified threshold. If one of the new values lies above
the threshold, the message
„Thresh.R.Endu.<“
is generated.
Three additional phase-selective statistic values are provided to determine the portion of purely mechanical
trips among the results of the remaining lifetime (e.g. for phase A:
„mechan.TRIP A=“
). They act as counters
which count only the trips whose tripping currents are below the value of the current criterion.
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