ABB RELION 670 Series Technical Manual page 230

Section 7
Impedance protection
I
•
AB
-
I
AB
ANSI07000110 V1 EN-US
Figure 100: Simplified offset mho characteristic and voltage vectors for phase A-to-B fault.
Operation occurs if 90≤β≤270.
Offset mho, forward direction
When forward direction has been selected for the offset mho, an extra criteria beside the one for
offset mho (90<β<270) is introduced, that is the angle φ between the voltage and the current
must lie between the blinders in second quadrant and fourth quadrant. See figure 101. Operation
occurs if 90≤β≤270 and
where
ArgDir
ArgNegRes
β
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 ,21D) for information about the mho directional
element.
224
I jX
AB
ZPP
V
• Z Re vPP
ArgDir≤φ≤ArgNegRes .
is the setting parameter for directional line in fourth quadrant in the directional
element, ZDMRDIR (21D).
is the setting parameter for directional line in second quadrant in the directional
element, ZDMRDIR (21D).
is calculated according to equation
V = V
-
comp1 I
AB
ß
Vcomp2 =
en07000110_ansi.vsd
• ZPP
AB
·
=IF
V
·ZF =V
AB
I R
AB
1MRK 502 066-UUS B
SEMOD154224-249 v4
Technical manual