ABB RELION 670 Series Technical Manual page 232

Section 7
Impedance protection
ANSI06000469 V1 EN-US
Figure 102: Operation characteristic for reverse phase A-to-B fault
Phase-to-ground fault
Mho
The measuring of ground faults uses ground-return compensation applied in a conventional way.
The compensation voltage is derived by considering the influence from the ground-return path.
For a ground fault in phase A, the compensation voltage Vcomp can be derived, as shown in Figure
103.
226
X
ZPP
ArgNegRes
ϕ
VAB
ZRevPP
IAB
ArgDir
R
en06000469_ansi.ep
1MRK 502 066-UUS B
SEMOD154224-283 v2
SEMOD154224-120 v5
Technical manual