ABB RELION REX640 Technical Manual page 879

1MRS759142 C
REX640
Technical Manual
Ris Gnd Rv Rch GFC, Ris PP Fwd Rch GFC and Ris PP Rv Rch GFC settings. The
characteristic is always mirror-symmetric around the reactance axis.
The impedance settings are in primary ohms.
In case of heavy loaded feeders, the optional load encroachment logic can be enabled
with the Load Dsr mode GFC setting. The logic reserves an area for load impedance
defined by the Ris Fwd Rch Lod GFC, Ris Rv Rch Lod GFC and Angle load area GFC
settings.
The underimpedance characteristics in case of phase-to-earth measuring elements are
illustrated in Figure 470
to-phase measuring elements with independent settings.
X
X Gnd Fwd reach GFC
Fault detected
X Gnd Rv reach GFC
GUID-E119694A-1ECB-4A92-B4BC-726F7B9E51E0 V1 EN
Figure 470: Circular mho underimpedance characteristics
X
X Gnd Fwd reach GFC
Fault detected
X Gnd Rv reach GFC
Ris Gnd Rv Rch GFC
GUID-B7E9AE53-7124-4469-960C-52B5646A14DA V1 EN
Figure 471: Quadrilateral underimpedance characteristics
and Figure 471. Similar characteristics apply also to phase-
Angle load area GFC
R
Ris Rv Rch Load GFC
Angle load area GFC
R
Ris Gnd Fwd Rch GFC
Section 4
Protection functions
X
Fault detected
Angle load area GFC
Ris Fwd Rch Load GFC
X
Fault detected
Angle load area GFC
Ris Rv Rch load GFC Ris Fwd Rch load GFC
R
R
873