ABB Relion 670 Series Technical Reference Manual page 336

Section 6
Impedance protection
330
RFRvPE
RFRvPE
RFRvPE
R1PE+RN
IEC09000633 V1 EN
Figure 170: Characteristic of FRPSPDIS (21) for phase to fault (directional lines
are drawn as "line-dot-dot-line")
Besides this, the 3I residual current must fulfil the conditions according to equation
0
and equation 28.
× ³ ×
3 I 0.5 IMinOpPE
0
EQUATION2108 V1 EN
3 I Enable PG _
× ³ ×
3 I 0 Iph
0
100
EQUATION1812-ANSI V1 EN
where:
IMinOpPE
is the minimum operation current for forward zones
3I Enable_PG is the setting for the minimum residual current needed to enable operation in the phase-to-
0
ground fault loops (in %).
Iphmax is the maximum phase current in any of three phases.
X (ohm/loop)
R1PE+RN
RFFwPE
RFFwPE
X1+XN
RFFwPE
max
1MRK505222-UUS C
X1+XN
R (Ohm/loop)
IEC09000633-1-en.vsd
Technical reference manual
27
(Equation 67)
(Equation 68)