ABB Relion 650 Series Technical Manual page 118

Section 5
Impedance protection
ANSI09000118 V1 EN-US
Figure 60: Simplified offset mho characteristic in forward direction for phase A-to-B fault
Offset mho, reverse direction
The operation area for offset mho in reverse direction is according to figure 61. The operation area
in second quadrant is
Operation occurs if 90≤β≤270 and 180° -
The β is derived according to equation for the mho circle and φ is the angle between the voltage
and current.
ANSI09000119 V1 EN-US
Figure 61: Operation characteristic for reverse phase A-to-B fault
112
I jX
AB
Z
V
AB
ArgNegRes
I
AB
ArgNegRes +180°.
X
Z
f
U
AB
ZRev
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ArgDir
ANSI09000118-1-en.vsd
ArgDir ≤φ ≤ ArgNegRes + 180°
ArgNegRes
I
AB
R
ArgDir
ANSI09000119-1-en.vsd
1MRK 506 326-UUS B
SEMOD154224-265 v4
Line distance protection REL650
Technical manual