6–74
345 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
S3 PROTECTION
CHAPTER 6: SETPOINTS
Figure 21: Instantaneous Differential Protection logic diagram
SETPOINT
SETPOINT
INST
DIFF
FUNCTION
:
Disabled
=
0
Latched
Alarm
INST
DIFFERENTIAL
PICKUP
:
AND
Operate
Output
Relay
1
((W1
BKR
TRIP
))
LED
:
TRIP
Alarm
OR
AND
T
rip
AND
SETPOINT
BLOCK
1:
Of
f
=
0
BLOCK
2:
Of
f
=
0
BLOCK
3:
Of
f
=
0
OR
OR
T
rip
(T
o
Breaker
Failure
)
Phase
A
Dif
f
current
(IAd
)
Phase
B
Dif
f
current
(IBd)
Phase
C
Dif
f
current
(ICd)
Phase
Differential
Currents
INST
DIFF
PKP
Message
LED:
PICKUP
IAd
=
Pickup
IBd
=
Pickup
ICd
=
Pickup
RUN
RUN
RUN
INST
DIFF
OP
Event
Recorder
OR
LED:
ALARM
RESET
Command
AND
S
R
LA
TCH
Operate
Output
Relay
2
((W1
BKR
TRIP
))
SETPOINT
:
Operate
output
relays
upon
selection
OUTPUT
RELA
Y
4
OUTPUT
RELA
Y
5
OUTPUT
RELA
Y
6
OUTPUT
RELA
Y
3
INST
DIFF
P
K
P
INST
DIFF
OP
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