ABB Relion 670 series - Page 285

7.7.6.2 Phase-to-phase fault
GUID-8C41B037-72E8-42EB-A5BA-9FA20BD830DB v1
For a phase-to-phase fault, the measured impedance by FRPSPDIS (21) is according to equation 79.
2
Vm Vn
ZPHS
In
-
=
- ×
EQUATION1813-ANSI V1 EN-US (Equation 79)
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.
IEC09000634-1-en.vsd
X1
R (ohm/phase)
X (ohm/phase)
0.5·RFFwPP
R1PP
R1PP
X1
0.5·RFFwPP
0.5·FRvPP
0.5·RFRvPP
0.5·RFRvPP
0.5·RFFwPP
IEC09000634 V1 EN-US
Figure 135: The operation characteristic for FRPSPDIS (21) at phase-to-phase fault
(directional lines are drawn as "line-dot-dot-line")
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
80 or
equation 81.
3 0 3 0 _I I Enable PG<
EQUATION1814-ANSI V1 EN-US
(Equation 80)
1MRK 502 066-UUS B Section 7
Impedance protection
279
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