(
)
1.2
2
³
×
-
Zrev
ZL Z rem
EQUATION1525 V5 EN-US
(Equation 190)
Where:
ZL
is the protected line impedance
Z2rem is zone 2 setting at remote end of protected line.
In some applications it might be necessary to consider the enlarging factor due to fault
current infeed from adjacent lines in the reverse direction in order to obtain certain sensitivity.
Parallel line in service
Setting of zones for parallel line application
GUID-27298DF4-E681-47D4-BD44-709F76B85344 v2
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:
Z
0m
A
B
Z<
Z<
IEC13000255-1-en.vsd
x
Ph-G
IEC13000255 V1 EN-US
Figure 145: 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 191)
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
Table continues on next page
Section 7
1MRK 505 343-UEN B
Impedance protection
234
Application manual
Содержание Relion 670 series
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