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5.136
SEL-421 Relay
Instruction Manual
Date Code 20171021
Protection Functions
Directional Comparison Unblocking Scheme Logic
Figure 5.98
DCUB Logic Diagram
UBDURD
0
G
ARD1D
UBEND
0
0
R
ela
y
Wo
rd
UBB2
LOG2
PT2
Loss
-o
f-Guar
d Input
Permissiv
e T
rip Input
Loss
-o
f-Guar
d Input
Pe
rmissiv
e T
rip Input
PT1
G
ARD1D
0
0
UBDURD
0
UBEND
Z3RB
Set
tings
Logic Enabled
if Set
ting
Lo
gic Enabled
EC
OMM
:= DCUB1
if Set
ting
or
EC
OMM := DCUB2
PTR
X2
UBB1
PTR
X1
Loss
-o
f-Channel
Loss
-o
f-Channel
R
ela
y
Wo
rd
Bit
SEL
OGIC
Bits
EC
OMM := DCUB2
LOG1
Set
tings
SEL
OGIC
Summary of Contents for SEL-421-4
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