ABB Relion 670 Series Technical Reference Manual page 418

Section 7
Current protection
412
SOTF
Open
Closed
SOTFSel
Close command
PUST2
StepForSOTF
PUST3
BLOCK
UNDERTIME
2nd Harmonic
EnHarmRestSOTF
Open
OR
Close
ActUndrTimeSel
Close command
PUST4
ANSI06000643 V3 EN
Figure 210: Simplified logic diagram for SOTF and Under-Time features
EF4PTOC (51N/67N) Logic Diagram Simplified logic diagram for the complete
EF4PTOC (51N/67N) function is shown in figure 211:
t4U
AND
AND
tUnderTime
AND
t
t4U
AND
1MRK505222-UUS C
tSOTF
t
OperationMode
Disabled
SOTF
TRIP
Undertime
Undertime
OR
ANSI06000643-3.vsd
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