ABB REL670 2.2 IEC - Page 258

Case 1: Parallel line switched-off and earthed at both ends:
Z
0m
A B
Z< Z<
IEC13000255-1-en.vsd
x
Ph-G
IEC13000255 V1 EN-US
Figure 129: The parallel line is out of service and earthed
0 1 0
1 0
1
1 (
1
)
3
Nm
N
m
K
Z x Z
K
Z Z Z
Z Z
+
= ×
+
-
-
×
IECEQUATION14011 V1 EN-US (Equation 168)
Where:
Z
1
is line positive sequence impedance
K
N
is earth compensation factor for single circuit set at the relay given
by equation
Z
0m
is the zero sequence mutual coupling between the faulted and the
parallel line
x is the ratio of distance to fault and length of the line
0 1
1
3
N
Z Z
K
Z
=
-
×
IECEQUATION14005 V1 EN-US (Equation 169)
K
Z
Z
Nm
m
=
⋅
0
1
3
IEC13000297 V1 EN-US (Equation 170)
Case 2: Parallel line switched off and not earthed or earthed at one line end
Section 8 1MRK 506 369-UEN B
Impedance protection
252 Line distance protection REL670 2.2 IEC
Application manual