ABB RELION REX640 Technical Manual page 1215

1MRS759142 F
• 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
and
limit has been set below Low alarm Dis limit , the ALARM operation is inverted: the
ALARM output is activated if
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.
REX640
Technical Manual
High alarm Dis limit , the ALARM output is activated. If setting High alarm Dis
High alarm Dis limit is undershot or Low alarm Dis limit
Protection related functions
Low alarm Dis limit
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