ABB RELION REX640 Technical Manual page 928

Protection functions
Characteristic
Reset time
Operate time accuracy
4.6.1.11 Technical revision history
Table 890: FRPRFQ Technical revision history
Product
connectivi
ty level
PCL4
4.6.2 Load-shedding and restoration LSHDPFRQ (ANSI 81LSH)
4.6.2.1 Identification
Function description
Load-shedding and restoration
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.
928
df/dt
Technical Change
revision
Operate Tm Freq maximum value extended to 5400000
F Setting
ms (90 mins).
IEC 61850 IEC 60617
identification identification
LSHDPFRQ UFLS/R
1MRS759142 F
Value
<120 ms
<150 ms
±1.0% of the set value or ±30
ms
ANSI/IEEE C37.2
device number
81LSH
REX640
Technical Manual