ABB Relion 670 Series Technical Reference Manual page 253

1MRK505222-UUS C
Technical reference manual
æ
V
-I ZPP
×
AB
b =
arg ç
V
-(-I ZRevPP)
è
×
AB
EQUATION1792-ANSI V1 EN
where
V
is the V voltage
AB
EQUATION1801 V1 EN
ZRevPP is the positive sequence impedance setting for phase-to-phase fault in reverse direction
I jX
AB
I • ZPP
AB
- • Z Re vPP
I
AB
ANSI07000110 V1 EN
Figure 119: 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 120. Operation occurs if 90≤β≤270 and ArgDir≤φ≤ArgNegRes.
ö
÷
ø
V = V
comp1
AB
ß
V
Vcomp2 =
Section 6
Impedance protection
(Equation 35)
-
I • ZPP
AB
·
=IF
V
·ZF =V
AB
I R
AB
en07000110_ansi.vsd
247