The β is derived according to equation 35 for the mho circle and φ is the angle between
the voltage and current.
X
R
ArgDir
ArgNegRes
ZPP
ZRevPP
VAB
ϕ
IAB
en06000469_ansi.ep
ANSI06000469 V1 EN
Figure 121: 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 122.
A loop
pol
Vcomp V I Z= - ×
EQUATION1793-ANSI V1 EN
(Equation 36)
1MRK505222-UUS C Section 6
Impedance protection
249
Technical reference manual
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