ABB RET670 - Page 298

ph ph
0 1 ph 0 N
ph 0
1
V V
Z Z I 3I K
I 3I
3 Z
Z = =
- + ×
+ ×
×
EQUATION1275 V2 EN (Equation 206)
Where:
Vph is phase-to-ground voltage at the IED point
Iph is phase current in the faulty phase
3I0 is ground to fault current
Z1 is positive sequence impedance
Z0 is zero sequence impedance
Z0m
A B
Z< Z<
en05000221.vsd
IEC05000221 V1 EN
Figure 130: Class 1, parallel line in service.
The equivalent circuit of the lines can be simplified, see figure 131.
A
B
C
Z0
m
Z0
Z0
m
-
Z0
Z0
m
-
99000038.vsd
IEC99000038 V1 EN
Figure 131: Equivalent zero sequence impedance circuit of the double-circuit,
parallel, operating line with a single phase-to-ground fault at the
remote busbar
When mutual coupling is introduced, the voltage at the IED point A will be changed.
Section 3 1MRK504116-UUS C
IED application
292
Application manual