ABB Relion 650 Series Technical Manual page 129

1MRK 506 326-UUS B
In systems where the source impedance for zero sequence is high the change of zero sequence
current may not be significant and the above detection may fail. In those cases the detection
enters the second level, with evaluation of zero and negative sequence voltage. The release of the
ground-fault loops can then be achieved if all of the following conditions are fulfilled:
|3V |>|V
0 2
|3V |>V
0 1
|V |> VBase · 0.2/√(3)
1
and
3I > 0.1 · IBase
0
or
3I <maxIph ·
0
where:
|3V |
0
V |
1
V |
2
maxIph
Phase-to-phase fault detection
The detection of phase-to-phase fault is performed by evaluation of the angle difference between
the sequence voltages V
180°
ANSI06000383 V1 EN-US
Figure 67: Definition of fault sectors for phase-to-phase fault
The phase-to-phase loop for the faulty phases will be determined if the angle between the
sequence voltages V
conditions are fulfilled:
V1MinOP
|V |>
1
Line distance protection REL650
Technical manual
| · 0.5
| · 0.2
INRelPG
is the magnitude of the zero sequence voltage
is the magnitude of the positive sequence voltage
is the magnitude of the negative sequence voltage
is the maximal phase current
and V
2 1
VC
C-A sector
VB
B-C sector
A-B sector
and V lies within the sector defined according to figure
2 1
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.
60°
0°
VA
300°
en06000383_ansi.vsd
Section 5
Impedance protection
SEMOD153832-119 v2
67 and the following
123