
I
A
jX
V
A
f
ArgDir
I
A
ArgNegRes
IA·R
en 06000466_ansi.vsd
ANSI06000466 V1 EN
Figure 47:
Simplified characteristic for offset mho in forward direction for A-to-
ground fault
Offset mho, reverse direction
In the same way as for offset in forward direction, the selection of offset mho in reverse
direction will introduce an extra criterion for operation compare to the normal offset mho.
The extra is that the angle between the fault voltage and the fault current shall lie between
the blinders in second and fourth quadrant. The operation area in second quadrant is
limited by the blinder defined as 180° -
ArgDir
and in fourth quadrant
ArgNegRes
+180°,
The conditions for operation of offset mho in reverse direction for A-to-ground fault is
90≤β≤270 and 180°-
Argdir
≤φ≤
ArgNegRes
+180°.
The β is derived according to equation
for the offset mho circle and φ is the angle
between the voltage and current.
1MRK 506 335-UUS A
Section 6
Impedance protection
119
Technical manual
Содержание REL650 series
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