The characteristic for FDPSPDIS (21) function at phase-to-ground fault is according to
figure 102. 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
25 and equation 26.
EQUATION1256 V1 EN (Equation 25)
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 27
and equation 28.
Section 6 1MRK505222-UUS C
Impedance protection
222
Technical reference manual
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