Characteristic Value
df/dt <120 ms
Reset time <150 ms
Operate time accuracy ±1.0% of the set value or ±30
ms
4.6.1.11 Technical revision history
Table 890: FRPRFQ Technical revision history
Product
connectivi
ty level
Technical
revision
Change
PCL4 F Setting
Operate Tm Freq
maximum value extended to 5400000
ms (90 mins).
4.6.2 Load-shedding and restoration LSHDPFRQ (ANSI 81LSH)
4.6.2.1 Identification
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Load-shedding and restoration LSHDPFRQ UFLS/R 81LSH
4.6.2.2 Function block
Figure 515: Function block
4.6.2.3 Functionality
The load-shedding and restoration function LSHDPFRQ is capable of performing
load-shedding based on underfrequency and the rate of change of the frequency.
The load that is shed during the frequency disturbance can be restored once the
frequency has stabilized to the normal level.
1
Applies to sudden frequency change of ≤0.2 Hz or to frequency slope of ≤ 5 Hz/s. When frequen-
cy change is outside of these limits, start may be delayed by additional 100 ms to prevent false
starts when connecting / disconnecting heavy loads.
Protection functions 1MRS759142 F
928 REX640
Technical Manual
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