ß
I
AB
·
X
I
AB
·R
-
en07000109_ansi.vsd
comp
AB
V
=V
AB
I ZPP
×
pol
V
AB
V
AB
I
ZPP
×
ANSI07000109 V1 EN
Figure 118:
Simplified mho characteristic and vector diagram for phase A-to-B fault
Offset Mho
The characteristic for offset mho is a circle where two points on the circle are the
setting parameters
ZPP
and
ZRevPP
. The vector ZPP in the impedance plane has the
settable angle
AngZPP
and the angle for
ZRevPP
is
180°
.
The condition for operation at phase-to-phase fault is that the angle β between the two
compensated voltages Vcomp1 and Vcomp2 is greater than or equal to 90° (figure
). The angle will be 90° for fault location on the boundary of the circle.
The angle β for A-to-B fault can be defined according to equation
Section 6
1MRK505222-UUS C
Impedance protection
246
Technical reference manual
Summary of Contents for Relion 670 series
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