ABB REL650 series Technical Manual page 119

1MRK 506 335-UUS A
Technical manual
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.
 
V I − ⋅ Z
AB
β =
Arg
 
( )
V − − I ⋅ Z v
 Re 
AB
EQUATION1792-ANSI-650 V1 EN
where
V
is the V voltage
AB
EQUATION1801 V1 EN
ZRev is the positive sequence impedance setting for phase-to-phase fault in reverse direction
I ·X
AB
I ·Z
AB
-
I ·ZRev
AB
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
=
V
Vcomp1
AB
ß
V
Vcomp2=V
I
AB
Section 6
Impedance protection
-
I ·Z
AB
=
I ·Z =V
F F AB
·R
ANSI09000117-1-en.vsd
(Equation 16)
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