ABB RET670 Applications Manual page 180

Section 3
IED application
174
-
Z Z
0 0m
I
0
A
-
Z Z
0 0m
B
IEC09000255 V1 EN
Figure 56: Equivalent zero-sequence impedance circuit for a double-circuit line
with one circuit disconnected and not grounded
The reduction of the reach is equal to equation 69.
(
1
× × +
2 Z Z
1 0 E
3
=
K
U
( )
1
× × +
2 Z Z
1 0
3
EQUATION1284 V1 EN
This means that the reach is reduced in reactive and resistive directions. If the real and
imaginary components of the constant A are equal to equation
= × × +
Re( ) A R 0 (2 R 1
EQUATION1285 V1 EN
= × × +
Im( ) A X (2 R
0 1
EQUATION1286 V1 EN
The real component of the KU factor is equal to equation 72.
( )
= +
Re K 1
U
é
Re
ë
EQUATION1287 V2 EN
The imaginary component of the same factor is equal to equation 73.
( )
×
Im A X
( )
=
Im K
U
( )
2
é ù
+
Re A
ë û
EQUATION1288 V2 EN
Z
0m
I
0
C
IEC09000255_1_en.vsd
)
+
R
Z
f
= -
1
(
× ×
Z 2 Z
+
R
1
0
f
+ × - ×
R 0 3 Rf ) X 0 ( 0 2 X
+ × + × ×
R 3 R ) R (2 X
0 1 0
( )
×
2
Re A X
m 0
( ) ( )
2 2
ù é ù
+
A Im A
û ë û
2
m 0
( )
2
é ù
Im A
ë û
1MRK504116-UUS C
2
m 0
)
+ +
Z 3 R
0
f
70 and equation 71.
+ ×
X 1)
+
X )
1 0
Application manual
(Equation 69)
(Equation 70)
(Equation 71)
(Equation 72)
(Equation 73)