ABB REL 356 Current Differential Protection
4-2
Measuring Elements and Operational Logic
IA
IB
IC
A/D
IT
DFT cosine
filter
Im(ITL) to transmitter
LDT
OP = |ITL + ITR|
RES = |ITL| + |ITR|
IF [OP - 0.7RES] > OTH
THEN trip
OTH
Im(IRL) from receiver
PLT (trip command)
Figure 4-2. Current Differential Logic
Operate quantity
[
] [
]
2
2
)
(
)
(
)
(
)
(
ITR
im
ITL
im
ITR
re
ITL
re
ITR
ITL
OP
+
+
+
=
+
=
Restraint quantity
[
] [
]
[
] [
]
2
2
2
2
)
(
)
(
)
(
)
(
ITR
im
ITR
re
ITL
im
ITL
re
ITR
ITL
RES
+
+
+
=
+
=
Trip decision
IF [(OP – 0.7RES) > OTH] THEN TRIP
Where
ITL = local quantity
ITR = remote quantity
OTH = set operating threshold
Summary of Contents for REL 356
Page 23: ...ABB REL 356 Current Differential Protection 1 10 Product Overview and Specifications ...
Page 83: ...ABB REL 356 Current Differential Protection 3 36 Settings and Application ...
Page 127: ...ABB REL 356 Current Differential Protection 5 28 Testing ...
Page 186: ...LINE SECTIONALIZING USING A PLC AND ABB PROTECTIVE RELAY Page 49 of 53 ...
Page 187: ...LINE SECTIONALIZING USING A PLC AND ABB PROTECTIVE RELAY Page 50 of 53 ...
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