ph
ph
0
1
ph
N
ph
0
1
0
V
V
Z
Z
I
3
K
I
3I
3 Z
I
Z
=
=
-
+
×
+
×
×
EQUATION1275 V3 EN-US
(Equation 27)
Where:
Vph
is phase-to-earth voltage at the IED point
Iph
is phase current in the faulty phase
3I0
is earth-fault current
Z1
is positive sequence impedance
Z0
is zero sequence impedance
Z0m
A
B
Z<
Z<
en05000221.vsd
IEC05000221 V1 EN-US
Figure 59:
Class 1, parallel line in service
The equivalent circuit of the lines can be simplified, as shown in figure
.
A
B
C
Z0m
Z0
Z0
m
-
Z0
Z0
m
-
99000038.vsd
IEC99000038 V1 EN-US
Figure 60:
Equivalent zero sequence impedance circuit of the double-circuit,
parallel, operating line with a single phase-to-earth-fault at the
remote busbar
When mutual coupling is introduced, the voltage at the IED point A is changed,
according to equation
Section 8
1MRK 506 369-UEN B
Impedance protection
154
Line distance protection REL670 2.2 IEC
Application manual
Summary of Contents for REL670 2.2 IEC
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