![background image](http://html1.mh-extra.com/html/abb/relion-670-series/relion-670-series_applications-manual_3052129161.webp)
The real component of the KU factor is equal to equation
Re
Re
Re
Im
K
A
X
A
A
u
m
( )
= +
( )
⋅
( )
+
( )
1
0
2
2
2
EQUATION1287 V3 EN-US
(Equation 61)
The imaginary component of the same factor is equal to equation
( )
( )
( )
( )
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 62)
Ensure that the underreaching zones from both line ends will overlap a sufficient amount (at
least 10%) in the middle of the protected circuit.
7.1.2.7
Tapped line application
SEMOD168232-266 v2
SEMOD168232-268 v2
A
B
Z<
Z<
Z<
C
T
I
C
I
A
I
B
-I
B
en05000224.vsd
DOCUMENT11524-IMG869 V1 EN-US
Figure 80: 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 is as
follows:
1MRK 505 343-UEN B
Section 7
Impedance protection
155
Application manual
Summary of Contents for Relion 670 series
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