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6–82
345 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
S3 PROTECTION
CHAPTER 6: SETPOINTS
Figure 25: Transformer Thermal Protection logic diagram
SE
TP
OINTS
Phase
A
curr
ent
(IA)
RUN
SE
TP
OINT
XFMR
THERMAL
FUNC
Disabled
=
0
Latched
Alarm
XFMR
THERMAL
PKP
AND
Phase
B
curr
ent
(IB)
Phase
C
curr
ent
(IC)
LED:
TRIP
Alarm
OR
OR
Phase
Curr
ents
AND
SE
TP
OINT
Operate
output
relays
upon
selection
OUTPUT
REL
AY
4
OUTPUT
REL
AY
5
OUTPUT
REL
AY
6
OUTPUT
REL
AY
3
Trip
AND
SE
TP
OINT
BL
OCK
1
O
ff=0
BL
OCK
2
O
ff=0
BL
OCK
3
O
ff=0
OR
XFMR
THERMAL
Ph
A
Thermal
OP
Ph
B
Thermal
OP
Ph
C
Thermal
OP
OR
XFMR
HE
A
TING
C
ONST
.
XFMR
C
OOLING
C
ONS
(ph
B)
(ph
C)
T
TRIP
(ph
A)
Thermal
Capacity
ph
A
,%
Thermal
Capacity
ph
B,
%
Thermal
Capacity
ph
C,
%
A
CTU
AL
V
A
L
UES
Ph
A
Thermal
Alarm
OR
SE
TP
OINT
XFMR
THERMAL
AL
ARM
ALARM
q
q>
Ph
B
Thermal
Alarm
Ph
C
Thermal
Alarm
LED:
AL
ARM
RESE
T
Command
AND
S
R
LA
TC
H
Operate
#2
Trip
(TRIP
W2
BKR)
Xfmr
Thermal
OP
Message
and
Ev
ent
Recor
der
Xfmr
Thermal
Alarm
Message
and
Ev
ent
Recor
der
T
TRIP
T
TRIP
Operate
#1
Trip
(TRIP
W1
BKR)
897815.
cdr
TRIP
(T
o
B
reaker
Failur
e)