Tapped Line Application - ABB RELION 670 SERIES Applications Manual

Section 8
Impedance protection
8.12.2.7
370
( )
×
Im A X
( )
=
Im K
U
( )
2
é ù
+
Re A
ë û
EQUATION1288 V2 EN
Ensure that the underreaching zones from both line ends will overlap a sufficient amount
(at least 10%) in the middle of the protected circuit.

Tapped line application

ANSI05000224 V2 EN
Figure 181: Example of tapped line with Auto transformer
This application gives rise to similar problem that was highlighted in section
of fault current infeed from remote line end"
to fault current infeed. For example, for faults between the T point and B station the
measured impedance at A and C will be
2
m 0
( )
2
é ù
Im A
ë û
A
, that is increased measured impedance due
1MRK 506 369-UUS -
B
C
ANSI05000224-2-en.vsd
Line distance protection REL670 2.2 ANSI
Application manual
(Equation 311)
BC
"Influence