ABB Relion 670 series - Page 375

distance protection zone is reduced if, due to operating conditions, the equivalent zero
sequence impedance is set according to the conditions when the parallel system is out of
operation and grounded at both ends.
A
B
C
IEC09000255_1_en.vsd
I
0
I
0
Z
0m
Z
0
-
Z
0m
Z
0m
Z
0
-
IEC09000255 V1 EN
Figure 180: 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 122.
( )
( )
( )
2
1 0
0
1 0
0
1 0
1
2
3
1
1
2 3
2
3
E f
m
U
f
f
Z Z R
Z
K
Z Z Z R
Z Z R
× × + +
= = -
× × + +
× × + +
EQUATION1284 V1 EN (Equation 307)
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 123 and equation 124.
Re( ) 0 (2 1 0 3 ) 0 ( 0 2 1)A R R R Rf X X X= × × + + × - × + ×
EQUATION1285 V1 EN
(Equation 308)
0 1 0 1 0 1 0
Im( ) (2 3 ) (2 )A X R R R R X X= × × + + × + × × +
EQUATION1286 V1 EN (Equation 309)
The real component of the KU factor is equal to equation 125.
Re
Re
Re Im
K
A X
A A
u
m
( )
= +
( )
⋅
( )




+
( )




1
0
2
2 2
EQUATION1287 V3 EN (Equation 310)
The imaginary component of the same factor is equal to equation 126.
1MRK 506 369-UUS - Section 8
Impedance protection
Line distance protection REL670 2.2 ANSI 369
Application manual