Design - ABB REG650 Technical Manual

1MRK 502 048-UEN A
10.3.6.3
BLOCK
freqNotValid
Rate-of-Change
of Frequency
Frequency
IEC08000009 V1 EN
Figure 155: Schematic design of Rate-of-change frequency protection SAPFRC
Technical manual
fulfilled again within a defined reset time, the START output is reset after the reset
time has elapsed.
After an issue of the TRIP output signal, the RESTORE output of SAPFRC is set after
a time delay (tRestore), when the measured frequency has returned to the level
corresponding to RestoreFreq. If tRestore is set to 0.000 s the restore functionality is
disabled, and no output will be given. The restore functionality is only active for
lowering frequency conditions and the restore sequence is disabled if a new negative
frequency gradient is detected during the restore period.

Design

Comparator
If
[StartFreqGrad<0
START
AND
df/dt < StartFreqGrad]
OR
[StartFreqGrad>0
AND
df/dt > StartFreqGrad]
Then
START
Comparator
f > RestoreFreq
BLOCK
OR
Definite Time Delay
tTrip
tRestore
Section 10
Frequency protection
BLKDMAGN
Start
&
Trip
Output
Logic
100 ms
RESTORE
IEC08000009_en_1.vsd
START
TRIP
305