Cross-polarizing as polarizing quantity
Table 274: Equations for calculating angle difference for cross-polarizing method
Faulted
phases
Used
fault
current
Used
polarizing
voltage
Angle difference
A
I
A
U
BC
ANGLE
A
U
I
BC
A
RCA
o
_
(
) -
(
) -
=
+
ϕ
ϕ
ϕ
90
B
I
B
U
CA
ANGLE
B
U
I
CA
B
RCA
o
_
(
) -
(
) -
=
+
ϕ
ϕ
ϕ
90
C
I
C
U
AB
ANGLE
C
U
I
AB
C
RCA
o
_
(
) -
(
) -
=
+
ϕ
ϕ
ϕ
90
A - B
I
A
- I
B
U
BC
- U
CA
ANGLE
A
U
U
I
I
BC
CA
A
B
RCA
o
_
(
-
) -
(
-
) -
=
+
ϕ
ϕ
ϕ
90
B - C
I
B
- I
C
U
CA
- U
AB
ANGLE
B
U
U
I
I
CA
AB
B
C
RCA
o
_
(
-
) -
(
-
) -
=
+
ϕ
ϕ
ϕ
90
C - A
I
C
- I
A
U
AB
- U
BC
ANGLE
C
U
U
I
I
AB
BC
C
A
RCA
o
_
(
-
) -
(
-
) -
=
+
ϕ
ϕ
ϕ
90
The angle difference between the polarizing quantity U
BC
and operating quantity I
A
is marked as φ in an example of the phasors in a single-phase earth fault where
the faulted phase is phase A. The polarizing quantity is rotated with 90 degrees. The
characteristic angle is assumed to be ~ 0 degrees.
Figure 140: Single-phase earth fault, phase A
In an example of the phasors in a two-phase short-circuit failure where the fault
is between the phases B and C, the angle difference is measured between the
polarizing quantity U
AB
and operating quantity I
B
- I
C
marked as φ.
1MRS757644 H
Protection functions
620 series
Technical Manual
283
