• Immediately after the fault occurrence, the estimate is affected by initial fault
transients in voltages and currents.
• Approximately one fundamental cycle after the fault occurrence, the fault
distance estimate starts to approach the final value.
• Approximately two fundamental cycles after the fault occurrence, the stability
criterion for fault distance estimate is fulfilled and the TRIGG_OUT event is sent.
The recorded data values are stored at this moment.
Figure 694: The behavior of fault distance estimate in time
5.7.5.5 Alarm indication
SCEFRFLO contains an alarm output for the calculated fault distance. If the
calculated fault distance FLT_DISTANCE is between the settings
Low alarm Dis limit
and
High alarm Dis limit
, the ALARM output is activated. If setting
High alarm Dis
limit
has been set below
Low alarm Dis limit
, the ALARM operation is inverted: the
ALARM output is activated if
High alarm Dis limit
is undershot or
Low alarm Dis limit
is exceeded. The default value for both is zero so that no distance estimate activates
ALARM.
The ALARM output can be utilized, for example, in regions with waterways or other
places where knowledge of certain fault locations is of high importance.
1MRS759142 F
Protection related functions
REX640
Technical Manual
1215
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