ABB RELION 620 Series Technical Manual page 861

1MRS757644 F
5.7.4.4
620 series
Technical Manual
Generally, SCEFRFLO requires a minimum of two fundamental cycles of measuring
time after the fault occurrence.
estimate of SCEFRFLO as a function of time.
• 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.
GUID-2C1E2C55-B61A-4200-BC8E-0F6FC9036A56 V3 EN
Figure 444: The behavior of fault distance estimate in time
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.
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.
Protection related functions
Figure 444 illustrates typical behavior of fault distance
Section 5
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