ABB RELION 670 SERIES Applications Manual page 275

1MRK 506 369-UUS -
Line distance protection REL670 2.2 ANSI
Application manual
Parallel line in service
Setting of zones for parallel line application
The distance protection zone reaches vary with the switching state of the parallel line
configuration. Below the configurations and the corresponding formulas for the reach
calculation are given for the most important cases. In these equations, x stands for ratio of
distance to fault and length of the line, and Z stands for the impedance seen by the relay.
Case 1: Parallel line switched-off and earthed at both ends:
ANSI13000255 V1 EN
Figure 131: The parallel line is out of service and earthed
-
Z Z
-
+ 0 1
1 (
3 Z
×
1
= ×
Z x Z
1
+
1 K
IECEQUATION14011 V1 EN
Where:
Z is line positive sequence impedance
1
K is earth compensation factor for single circuit set at the relay given by
N
equation
Z is the zero sequence mutual coupling between the faulted and the
0m
parallel line
x is the ratio of distance to fault and length of the line
-
Z Z
K 0 1
=
N
×
3 Z
1
IECEQUATION14005 V1 EN
Z
0 m
K
=
Nm
3 Z
⋅
1
IEC13000297 V1 EN
Z
)
0 m
K
Nm Z
0
N
Section 8
Impedance protection
(Equation 171)
(Equation 172)
(Equation 173)
269