ß
Rev
Z
•
-
)
=
ZRev
•
(-
-
Vcomp2
I
A
V
A
ANSI09000121-1-en.vsd
I
A
·
Z
I
AB·
jX
A
Vcomp1
V
=
-
I
A
·
Z
I
AB·
R
V
A
I
A
ANSI09000121 V1 EN
Figure 46:
Simplified offset mho characteristic and voltage vector for phase A-to-
ground fault
Operation occurs if 90≤β≤270.
Offset mho, forward direction
In the same way as for phase-to-phase fault, selection of forward direction of offset mho
will introduce an extra criterion for operation. Beside the basic criteria for offset mho
according to equation
and 90≤β≤270, also the criteria that the angle φ between the
voltage and the current must lie between the blinders in second and fourth quadrant. See
figure
. Operation occurs if 90≤β≤270 and
ArgDir
≤φ≤
ArgNegRes.
where
ArgDir
is the setting parameter for directional line in fourth quadrant in the directional element,
ZDNRDIR.
ArgNegRes
is the setting parameter for directional line in second quadrant in the directional element,
ZDNRDIR.
β
is calculated according to equation
Section 6
1MRK 506 335-UUS A
Impedance protection
118
Technical manual
Содержание REL650 series
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