ABB Relion 670 series, Technical Manual

Page: 230 / 1432

ZPP I
AB
•
AB
comp1
V = V
ß
I
AB
jX
I
AB
R
-
ZPP I
AB
•
vPP Re Z
AB
I
•
V
V Vcomp2 =
·
-
=IF
·ZF =V
AB
en07000110_ansi.vsd
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
SEMOD154224-249 v4
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
ArgDir≤φ≤ArgNegRes.
where
ArgDir
is the setting parameter for directional line in fourth quadrant in the directional
element, ZDMRDIR (21D).
ArgNegRes
is the setting parameter for directional line in second quadrant in the directional
element, ZDMRDIR (21D).
β is calculated according to equation
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.
Section 7 1MRK 502 066-UUS B
Impedance protection
224
Technical manual