Parallel line in service
SEMOD154680-175 v2
This type of application is very common and applies to all normal sub-transmission
and transmission networks.
A simplified single line diagram is shown in figure 141.
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 164)
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-US
Figure 141: Class 1, parallel line in service.
The equivalent circuit of the lines can be simplified, see figure
142.
1MRK 504 163-UUS A Section 8
Impedance protection
Transformer protection RET670 2.2 ANSI 299
Application manual
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