ABB RELION REX640 Technical Manual page 344

Section 4
Protection functions
338
Negative sequence voltage as polarizing quantity
When the negative voltage is used as the polarizing quantity, the angle difference
between the operating and polarizing quantity is calculated with the same formula for
all fault types:
ANGLE X U
_ ( )
ϕ ϕ
= − −
2
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This means that the actuating polarizing quantity is -U
I
A
U
A
I
2
U U
CA
I
I
B
U
C
2
U
U
C
BC
A
GUID-951670B8-DB76-41EA-A227-573C0F16408A V1 EN
Figure 191: Phasors in a single-phase earth fault, phases A-N, and two-phase
short circuit, phases B and C, when the actuating polarizing quantity
is the negative-sequence voltage -U2
Positive sequence voltage as polarizing quantity
Table 372: Equations for calculating angle difference for positive-sequence quantity polarizing
method
Faulted Used fault Used
phases current polarizing
voltage
A I U
A 1
B I U
B 1
C I U
C 1
Table continues on next page
I
( )
ϕ
−
2 RCA
I
C
AB
U
B
Angle difference
ANGLE A U
_ (
ϕ
=
1
GUID-BCA3F3AB-A4E6-4C2B-930C-5B224E98775D V1 EN
ANGLE B U
_ (
ϕ
=
1
GUID-0D8F3DB2-72EF-4CFD-94CD-145898410E51 V1 EN
ANGLE C U
_ (
ϕ
=
1
GUID-E722DC91-53CF-4A50-BE4D-3AE1FD8F5855 V1 EN
1MRS759142 C
.
2
U
A
I
U
A
2
I
2
U U
C B
B
I
) ( )
ϕ ϕ
− −
A RCA
I
) ( ) 120 o
ϕ ϕ
− − −
B RCA
I
) ( ) 120 o
ϕ ϕ
− − +
C RCA
Technical Manual
(Equation 20)
I
B
(Equation 21)
(Equation 22)
(Equation 23)
REX640