CHAPTER 4: SETPOINTS CONTROL
850 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL 4–353
Figure 4-155: Underfrequency Restoration logic diagram
FAST PATH:
Upon voltage and frequency recovery (measured frequency above programmed
minimum), and “Close” output relay selected as Self-Reset type, the UF Restore operating
condition and hence the Close output relay will reset automatically after the breaker is
detected closed. If the “Close” output relay is selected as Pulsed type, the output relay will
stay closed, until the programmed Seal-In time expires.
894070A3.cdr
LED: PICKUP
SETPOINTS
BLOCK:
Off=0
AND
SETPOINTS
UF RESTORE
FUNCTION:
Disabled
Alarm
Latched Alarm
Configurable
OR
The Voltage Input is the same as the one used for UF or Freq.
ROC element selected under the setpoint
“UF Restore initiation”
None
AND
SETPOINTS
UF RESTORE
MINIMUM FREQUENCY:
f
MINIMUM
FREQUENCY f
RUN
SETPOINTS
UF RESTORE
RESTORE DELAY:
t
RSR
0
UF Restore OP
FlexLogic Operands
UF Restore PKP
AND AND
Command
RESET
OR
LED: ALARM
WYE DELTA
VA
VAB
VB VBC
VC VCA
OR
AND
Command
RESET
SETPOINTS
UF RESTORE
INCOMPLETE
SEQUENCE TIME:
t
IST
0
Status Input
to BKR1 Close Relay
Select output relay
Vx
Positive-
sequence,
Composite or
Auxiliary Voltage
SETPOINTS
UF RESTORE
MINIMUM VOLTAGE:
V
MINIMUM
RUN
S
LATCH
Set-
Dominant
R
SETPOINTS
UF RESTORE
INITIATION:
Off = 0,
Underfreq 1 OP,
«
Underfreq 6 OP,
Freq Rate 1 DWN OP,
«
Freq Rate 6
DWN OP
Close
AND
SETPOINTS
OUTPUT RELAYS (3 -7):
Do Not Operate, Operate
UF Restore Init
AND
from BKR1 Status
FlexLogic Operand
BKR 1 Closed
FlexLogic Operand
BKR 1 Closed
BKR 1 OpenBKR 1 Open
SETPOINT
SYNCHROCHECK
SUPERVISION:
Bypass
Sync1 Close Perm
Sync1 Close Perm
From Synchrocheck 1
ANDAND
OR
Sync2 Close Perm
From Synchrocheck 2
ANDAND
Sync2 Close Perm
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