ABB REG670 - Page 193

voltage and the current must lie between the blinders in second quadrant and fourth
quadrant. See figure 68. Operation occurs if 90≤β≤270 and ArgDir≤φ≤ArgNegRes.
where
ArgDir is the setting parameter for directional line in fourth quadrant in the directional element,
ZDMRDIR.
ArgNegRes is the setting parameter for directional line in second quadrant in the directional element,
ZDMRDIR.
β is calculated according to equation 38
The directional information is brought to the mho distance measurement from the mho
directional element as binary coded information to the input DIRCND. See
Directional impedance element for mho characteristic (ZDMRDIR) for information
about the mho directional element.
IL1L2jX
UL1L2
f
ArgDir
IL1L2
ArgNegRes
ZPP
en07000111.vsd
IEC07000111 V1 EN
Figure 68: Simplified offset mho characteristic in forward direction for phase L1-
to-L2 fault
Offset mho, reverse direction
The operation area for offset mho in reverse direction is according to figure 69. The
operation area in second quadrant is ArgNegRes+180°.
Operation occurs if 90≤β≤270 and 180° - ArgDir ≤φ ≤ ArgNegRes + 180°
The β is derived according to equation 38 for the mho circle and φ is the angle between
the voltage and current.
1MRK502052-UEN B Section 7
Impedance protection
187
Technical manual