ABB Relion 670 series - Page 434

X
0E
X
0
X
m0
+=
EQUATION554 V1 EN (Equation 384)
Check the reduction of a reach for the overreaching zones due to the effect of the zero
sequence mutual coupling. The reach is reduced for a factor:
0
0 1
2 1 0
m
f
Z
K
Z Z R
= -
× + +
EQUATION1426 V1 EN (Equation 385)
If the denominator in equation 134 is called B and Z0m is simplified to X0m, then the real
and imaginary part of the reach reduction factor for the overreaching zones can be written
as:
( )
( )
( ) ( )
2 2
0 Re
Re 0 1
Re Im
X m B
K
B B
×
= -
+
EQUATION1427 V2 EN (Equation 386)
( )
( )
( ) ( )
2 2
0 Im
Im 0
Re Im
X m B
K
B B
×
=
+
EQUATION1428 V2 EN (Equation 387)
Parallel line is out of service and grounded in both ends
Apply the same measures as in the case with a single set of setting parameters. This means
that an underreaching zone must not overreach the end of a protected circuit for the single
phase-to-ground faults.
Set the values of the corresponding zone (zero-sequence resistance and reactance) equal
to:
R
0E
R
0
1
X
m0
2
R
0
2
X
0
2
+
--------------------------
+
è ø
ç ÷
æ ö
×=
EQUATION561 V1 EN (Equation 388)
X
0E
X
0
1
X
m0
2
R
0
2
X
0
2
+
--------------------------
–
è ø
ç ÷
æ ö
×=
EQUATION562 V1 EN (Equation 389)
Section 8 1MRK 506 369-UUS -
Impedance protection
428 Line distance protection REL670 2.2 ANSI
Application manual