ABB RELION 670 SERIES Applications Manual page 196

Section 8
Impedance protection
190
near the feeding bus will see in different cases fault on remote end bus depending on type
of overvoltage protection used on capacitor bank (spark gap or MOV) and SC location on
protected power line.
50 %
33%
0%
E
~
A
K 80%
=
C
21
ANSI06000612 V1 EN
Figure 88: Typical locations of capacitor banks on series compensated line
Implementation of spark gaps for capacitor overvoltage protection makes the picture
relatively simple, because they either flash over or not. The apparent impedance
corresponds to the impedance of non-compensated line, as shown in figure
0%.
KC = 80%
KC = 0% LOC = 0%
R R
IEC06000613 V1 EN
Figure 89: Apparent impedances seen by distance IED for different SC locations
and spark gaps used for overvoltage protection
100 %
66%
33 % 50 % 33%
KC = 50% KC = 2 x 33% KC = 80%
LOC = 50% LOC = 33%, 66% LOC = 100%
R R R
en06000613.vsd
1MRK 506 369-UUS -
X
80 %
en06000612_ansi.vsd
89 case K
Line distance protection REL670 2.2 ANSI
Application manual
=
C