ABB RELION 670 SERIES Applications Manual page 328

Section 8
Impedance protection
322
2 2
-
Z Z
0 om
=
Z
E
Z
0
EQUATION2002 V4 EN
The influence on the distance measurement will be a considerable overreach, which must
be considered when calculating the settings. It is recommended to use a separate setting
group for this operation condition since it will reduce the reach considerably when the line
is in operation.
All expressions below are proposed for practical use. They assume the value of zero
sequence, mutual resistance R
mutual reactance X . Calculate the equivalent X
0m
according to equation 120
for calculating the reach for the underreaching zone.

X
0 m
1
R R
= ⋅  +
0 0
E
2

R
+

0
DOCUMENT11520-IMG3502 V2 EN

X
0
1
X X
= ⋅  −
0 E 0
2

R
+

0
DOCUMENT11520-IMG3503 V2 EN
Parallel line out of service and not grounded
A
OPEN
CLOSED
21
ANSI05000223 V1 EN
Figure 156: Parallel line is out of service and not grounded.
equals to zero. They consider only the zero sequence,
0m
and equation 121 for each particular line section and use them
2


2

X

0
2

m

2

X

0
B
OPEN
Z0m
CLOSED
21
en05000223_ansi.vsd
1MRK 506 369-UUS -
and R zero sequence parameters
0E 0E
Line distance protection REL670 2.2 ANSI
Application manual
(Equation 246)
(Equation 247)
(Equation 248)