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CHAPTER 6: SETPOINTS
S3 PROTECTION
350 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
6–107
Figure 36: Underfrequency logic diagram
Phase
V
oltage
Inputs
(associated
setpoints)
SETPOINTS
Va
b
SETPOINT
UNDERFREQ
FUNCTN:
Disabled
=
0
Latched
Alarm
UNDERFREQ
PKP:
Vbc
Vca
Operate
Output
Relay
1
(TRIP)
Event
Recorder
T
ransient
Recorder
LED:
TRIP
Alarm
OR
OR
AND
SETPOINTS
Operate
output
relays
upon
selection
OUTPUT
RELA
Y
4
OUTPUT
RELA
Y
5
OUTPUT
RELA
Y
6
OUTPUT
RELA
Y
3
T
rip
AND
Tr
ip
(T
o
Breaker
Failure)
SETPOINTS
BLOCK
1:
O
ff=0
BLOCK
2:
O
ff=0
BLOCK
3:
O
ff=0
OR
RUN
Va
n
Vbn
Vcn
None
AND
Delta
Wy
e
LED:
PICKUP
Event
Recorder
T
ransient
Recorder
Underfrequency1(2)
Message
f
<
PICKUP
Frequency
Measurement
f
(
V
a)
-
frequency
V
a
>
Minimum
MIN
VOL
T
AGE:
SETPOINT
f=0
UNDERFREQ
DELA
Y
:
SETPOINT
t
PKP
LED:
ALARM
RESET
Command
AND
S
R
LA
TCH
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