ABB REL650 series, Техническое руководство

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The positive sequence voltage V
1
A in figure 67 above is reference.
If there is a three-phase fault, there will not be any release of the individual phase signals,
even if the general conditions for V
2
and V
1
are fulfilled.
Phase-to-ground and phase-to-phase-to-ground-fault detection
The detection of phase-to-ground and phase-to-phase-to-ground fault (US patent
5390067) is based on two conditions:
1. Angle relationship between V
2
and I
0
2. Angle relationship between V
2
and V
1
The condition 1 determines faulty phase at single phase-to-ground fault by determine the
angle between V
2
and I
0
.
320°
200°
80°
AG sector
CG sector
BG sector
V2A
(Ref)
en06000384_ansi.vsd
ANSI06000384 V1 EN
Figure 68: Condition 1: Definition of faulty phase sector as angle between V
2
and I
0
The angle is calculated in a directional function block and gives the angle in radians as
input to the V
2
and I
0
function block. The input angle is released only if the fault is in
forward direction. This is done by the directional element. The fault is classified as
forward direction if the angle between V
0
and I
0
lies between 20 to 200 degrees, see figure
69 .
Section 6
1MRK 506 335-UUS A
Impedance protection
154
Technical manual