The characteristic for FDPSPDIS (21) function at phase-to-ground fault is according to
figure
. The characteristic has a fixed angle for the resistive boundary in the first
quadrant of 60°.
The resistance RN and reactance XN are the impedance in the ground-return path
defined according to equation
0
1
3
R
R
RN
-
=
EQUATION1256 V1 EN
(Equation 25)
0
1
3
X
X
XN
-
=
EQUATION1257 V1 EN
(Equation 26)
en06000396_ansi.vsd
RFItFwdPG
X1
+XN
R
(Ohm/loop)
X
(ohm/loop)
RFItRevPG
RFItRevPG
RFItFwdPG
Kr·(
X1
+XN)
RFItRevPG
Kr·(
X1
+XN)
X1+
XN
RFItFwdPG
60 deg
60 deg
=
1
Kr
tan(60 deg)
ANSI06000396 V1 EN
Figure 102:
Characteristic of FDPSPDIS (21) for phase-to-ground fault (setting
parameters in italic), ohm/loop domain (directional lines are drawn as
"line-dot-dot-line")
Besides this, the 3I
0
residual current must fulfil the conditions according to equation
Section 6
1MRK505222-UUS C
Impedance protection
222
Technical reference manual
Summary of Contents for Relion 670 series
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