ABB RET670 Applications Manual page 250

Section 3
IED application
244
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:
Z 0
m
= -
K 0 1
× + +
2 Z 1 Z 0 R
f
EQUATION1426 V1 EN
If the denominator in equation
real and imaginary part of the reach reduction factor for the overreaching zones can be
written as:
×
X m 0 Re
( )
= -
Re K 0 1
( )
2
+
Re B Im
EQUATION1427 V2 EN
( )
×
X m 0 Im
( )
=
Im K 0
( )
2
+
Re B Im
EQUATION1428 V2 EN
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:
2
æ
X
m0
×
ç ------------------------- -
R = R 1 +
0E 0
2 2
è
R X
+
0 0
EQUATION561 V1 EN
2
æ X
m0
×
X = X ç 1 – ------------------------- -
0E 0
2 2
è
R X
+
0 0
EQUATION562 V1 EN
Setting of reach in resistive direction
Set the resistive reach independently for each zone, and separately for phase-to-phase
(R1PP), and phase-to-ground loop (R1PG) measurement.
Set separately the expected fault resistance for phase-to-phase faults (R1PP) and for
the phase-to-ground faults (RFPG) for each zone. Set all remaining reach setting
parameters independently of each other for each distance zone.
155 is called B and Z0m is simplified to X0m, then the
( )
B
( )
2
B
B
( )
2
B
ö
÷
ø
ö
÷
ø
1MRK504116-UUS C
(Equation 155)
(Equation 156)
(Equation 157)
(Equation 158)
(Equation 159)
Application manual