Tapped Line Application - ABB RELION 670 Series Applications Manual

1MRK 504 152-UEN B
The real component of the KU factor is equal to equation 55.
( )
K
Re
EQUATION1287 V3 EN-US
The imaginary component of the same factor is equal to equation 56.
( )
Im K
U
EQUATION1288 V2 EN-US
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

DOCUMENT11524-IMG869 V1 EN-US
Figure 65: Example of tapped line with Auto transformer
This application gives rise to similar problem that was highlighted in section
from remote end"
example, for faults between the T point and B station the measured impedance at A and C is as
follows:
Application manual
( )
A X
Re
= +
1
u
2
( )
 
A
Re
 
( )
× 2
Im A X
m 0
=
( ) ( )
2
é ù é
+
Re A Im A
ë û ë
A
I
A
Z<
Z<
that is, increased measured impedance due to fault current infeed. For
⋅ 2
m
0
2
( )
 
+
A
Im
 
2
ù
û
I
B
T
Z<
I
C
C
Impedance protection
B
-I
B
en05000224.vsd
"Fault infeed
Section 7
(Equation 55)
(Equation 56)
SEMOD168232-266 v2
SEMOD168232-268 v2
155