Load Encroachment - ABB Relion 670 Series Technical Reference Manual

1MRK505222-UUS C
6.10.2.4
Technical reference manual
×
4 X1PP
X1·K3
K3 = 2 / sqrt(3)
IEC09000635 V2 EN
Figure 172: The characteristic of FRPSPDIS (21) for three-phase fault (set angle 70°)

Load encroachment

Each of the six measuring loops has its own load encroachment characteristic based on
the corresponding loop impedance. The load encroachment functionality is always
active, but can be switched off by selecting a high setting.
The outline of the characteristic is presented in figure 106. As illustrated, the resistive
blinders are set individually in forward and reverse direction while the angle of the
sector is the same in all four quadrants.
X (ohm/phase)
3
0.5·RFFwPP·K3
30 deg
0.5·RFRvPP·K3
Section 6
Impedance protection
2
RFwPP ×
3
R (ohm/phase)
30 deg
IEC09000635-1-en.vsd
333