ABB REL670 2.2 IEC - Page 305

ph ph
0 1 ph 0 N
ph 0
1
U U
Z Z I 3I K
I 3I
3 Z
Z = =
- + ×
+ ×
×
EQUATION2311 V1 EN-US (Equation 236)
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 236)
Where:
U
ph
is phase to earth voltage at the relay point
I
ph
is phase current in the faulty phase
3I
0
is earth fault current
Z
1
is positive sequence impedance
Z
0
is zero sequence impedance
Z
0m
A B
Z< Z<
IEC09000250_1_en.vsd
IEC09000250 V1 EN-US
Figure 150: Class 1, parallel line in service.
The equivalent zero sequence circuit of the lines can be simplified, see figure 151.
A
B
C
Z
0m
Z
0m
Z
0
-
Z
0m
Z
0
-
IEC09000253_1_en.vsd
IEC09000253 V1 EN-US
Figure 151: 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 relay point A will be
changed according to equation 237.
1MRK 506 369-UEN B Section 8
Impedance protection
Line distance protection REL670 2.2 IEC 299
Application manual