ABB Relion 670 series - Page 147

Internal/
External
Fault
discrimin
ator
t
PU_A
PU_B
PU_C
OR
AND
EXTFAULT
INTFAULT
TRNSSENS
T R N S U N
R
en05000167_ansi.vsd
Constant
IBIAS
a
b
b>a
Neg.Seq. Diff
Current
Contributions
OpNegSeqDiff=On
AND
BLKNSSEN
BLKNSUNR
BLOCK
0
ANSI05000167 V1 EN-US
Figure 43: Transformer differential protection simplified logic diagram for external/internal
fault discriminator
en05000278_ansi.vsd
TRIPRES_A
TRIPRES_B
TRIPRES_C
OR
TRIPRES
TRIPUNRE_A
TRIPUNRE_B
TRIPUNRE_C
OR
TRIPUNRE
OR
TRIP
TRNSUNR
TRNSSENS
ANSI05000278 V1 EN-US
Figure 44: Transformer differential protection internal grouping of tripping signals
1MRK 502 066-UUS B Section 6
Differential protection
141
Technical manual