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1MRK 502 071-UUS A
Generator protection REG670 2.2 ANSI and Injection equipment REX060, REX061, REX062
Application manual
From symmetrical components, we can derive the impedance Z at the relay point for
normal lines without mutual coupling according to equation 82.
V
V
ph
Z =
=
I
-
+
Z
Z
I
3
0
1
ph
+
×
I
3I
ph
0
×
3 Z
1
EQUATION1275 V3 EN-US
Where:
Vph
is phase to ground voltage at the relay point.
Iph
is phase current in the faulty phase.
3I0
is ground fault current.
Z1
is positive sequence impedance.
Z0
is zero sequence impedance.
A
21
ANSI05000221 V1 EN-US
Figure 99:
Class 1, parallel line in service
The equivalent circuit of the lines can be simplified, see figure 100.
-
Z
Z
0
0m
A
-
Z
Z
0
0m
B
IEC09000253 V1 EN-US
Figure 100:
Equivalent zero sequence impedance circuit of the double-circuit,
parallel, operating line with a single phase-to-ground fault at the
remote busbar
ph
×
K
N
0
FAULT
Z0m
Z
0m
IEC09000253_1_en.vsd
Section 8
Impedance protection
B
21
en05000221_ansi.vsd
C
(Equation 82)
237
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