ABB RELION REX640 - Page 955

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 529 and Figure 530 . Similar characteristics apply also to
phase-to-phase measuring elements with independent settings.
R
X
X
Gnd Fwd reach GFC
X Gnd Rv reach GFC
R
X
Angle load area GFC
Ris Fwd Rch Load GFC
Fault detected
Fault detected
Angle load area GFC
Ris Rv Rch Load GFC
Figure 529: Circular mho underimpedance characteristics
R
X
X
Gnd Fwd reach GFC
X Gnd Rv reach GFC
R
X
Angle load area GFC
Ris Fwd Rch load GFC
Fault detected
Fault detected
Angle load area GFC
Ris Gnd Fwd Rch GFCRis Gnd Rv Rch GFC
Ris Rv Rch load GFC
Figure 530: Quadrilateral underimpedance characteristics
Table 914: Conversion from element start to monitored data signals
Start of element START_GFC STARTS_GF
C
RELEASE_P
E
RELEASE_P
P
Z
A
< &
EARTH_FLT
TRUE AG Fault AG Fault No fault
Z
B
< &
EARTH_FLT
TRUE BG Fault BG Fault No fault
Z
C
< &
EARTH_FLT
TRUE CG Fault CG Fault No fault
Z
AB
<
TRUE AB Fault No fault AB Fault
Z
BC
<
TRUE BC Fault No fault BC Fault
Z
CA
<
TRUE CA Fault No fault CA Fault
Table continues on the next page
1MRS759142 F Protection functions
REX640
Technical Manual
955