ABB 615 series Technical Manual page 827

1MAC059074-MB A
615 series ANSI
Technical Manual
Table 715: Impedance settings
Parameter
R1 line section A
X1 line section A
Line Len section A
R1 line section B
X1 line section B
Line Len section B
R1 line section C
X1 line section C
Line Len section C
Figure 419 illustrates the conversion error from measured fault loop reactance into
physical fault distance. The fault location is varied from 1 km to 10 km in 1 km steps
(marked with circles). An error of nearly eight per cent at maximum is created by the
conversion procedure when modeling a non-homogenous line with only one section. By
using impedance model with three line sections, there is no error in the conversion.
The previous example assumed a short circuit fault and thus, only positive-sequence
impedance settings were used. The results, however, also apply for ground faults.
Taps or spurs in the feeder
If the protected feeder consists of taps or spurs, the measured fault impedance corresponds
to several physical fault locations (For example, A or B in
location must be identified using additional information, for example, short circuit current
indicators placed on tapping points.
Protection related functions
Impedance model with one section Impedance model with three
0.660 Ω/pu
0.341 Ω/pu
10000 pu
N/A
N/A
0.000 pu
N/A
N/A
0.000 pu
Section 5
sections
0.236 Ω/pu
0.276 Ω/pu
4000 pu
0.536 Ω/pu
0.369 Ω/pu
3000 pu
1.350 Ω/pu
0.398 Ω/pu
3000 pu
Figure 420). The actual fault
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