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( )
( )
( )
( )
2
0
2
2
Im
Im
Re
Im
m
U
A X
K
A
A
×
=
+
é
ù
é
ù
ë
û
ë
û
EQUATION1288 V2 EN-US
(Equation 223)
Ensure that the underreaching zones from both line ends will overlap a sufficient amount (at
least 10%) in the middle of the protected circuit.
7.5.2.8
Tapped line application
SEMOD154680-265 v1
SEMOD154680-267 v2
A
B
Z<
Z<
Z<
C
T
I
C
I
A
I
B
-I
B
en05000224.vsd
DOCUMENT11524-IMG869 V1 EN-US
Figure 159: Example of tapped line with Auto transformer
This application gives rise to similar problem that was highlighted in section
that is, increased measured impedance due to fault current infeed. For
example for faults between the T point and B station the measured impedance at A and C will
be
Z
A
=Z
AT
+ ·Z
TF
I
A
+ I
C
I
A
DOCUMENT11524-IMG3509 V3 EN-US
(Equation 224)
Z
Z
Z
I
I
I
Z
U
U
C
Trf
CT
A
C
C
TF
=
+
+
+
⋅
⋅
2
1
2
DOCUMENT11524-IMG3510 V3 EN-US
(Equation 225)
1MRK 505 343-UEN B
Section 7
Impedance protection
253
Application manual
Summary of Contents for Relion 670 series
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