ABB REL650 series, Technical Manual

Page: 119 / 856

The condition for operation at phase-to-phase fault is that the angle β between the two
compensated voltages Vcomp1 and Vcomp2 is greater than or equal to 90° (figure
42 ).
The angle will be 90° for fault location on the boundary of the circle.
The angle β for A-to-B fault can be defined according to equation 16 .
β
=






− ⋅
− − ⋅
( )
Arg
V I Z
V I Z v
AB
AB
Re
EQUATION1792-ANSI-650 V1 EN
(Equation 16)
where
V
EQUATION1801 V1 EN
is the V
AB
voltage
ZRev is the positive sequence impedance setting for phase-to-phase fault in reverse direction
ß
V
-
ANSI09000117-1-en.vsd
I
AB
·X
I
AB
·Z
AB
Vcomp1
V =
-
I
AB
· Z
Vcomp2 =V
=
I
F
· Z
F
=V
AB
I
AB
·R
I
AB
· ZRev
ANSI09000117 V1 EN
Figure 42: Simplified offset mho characteristic and voltage vectors for phase A-to-B
fault.
Operation occurs if 90≤β≤270.
Offset mho, forward direction
1MRK 506 335-UUS A
Section 6
Impedance protection
113
Technical manual