ABB RELION 670 Series Technical Manual page 285

1MRK 502 066-UUS B
7.7.6.2 Phase-to-phase fault
For a phase-to-phase fault, the measured impedance by FRPSPDIS (21) is according to equation 79.
=
ZPHS
EQUATION1813-ANSI V1 EN-US
Vm is the leading phase voltage, Vn the lagging phase voltage and In the phase current in the
lagging phase n.
The operation characteristic is shown in figure 135.
0.5·RFRvPP
IEC09000634 V1 EN-US
Figure 135: The operation characteristic for FRPSPDIS (21) at phase-to-phase fault
In the same way as the condition for phase-to-ground fault, there are current conditions that have
to be fulfilled in order to release the phase-to-phase loop. Those are according to equation
equation 81.
<
3 0 I 3 0 I Enable PG
EQUATION1814-ANSI V1 EN-US
Technical manual
-
Vm Vn
- ×
2 In
X (ohm/phase)
0.5·FRvPP
R1PP
0.5·RFFwPP
0.5·RFRvPP
R1PP
0.5·RFFwPP
(directional lines are drawn as "line-dot-dot-line")
_
0.5·RFFwPP
X1
R (ohm/phase)
X1
IEC09000634-1-en.vsd
Section 7
Impedance protection
GUID-8C41B037-72E8-42EB-A5BA-9FA20BD830DB v1
(Equation 79)
80 or
(Equation 80)
279