ABB RELION REX640 - Page 357

U
A
U
B
U
C
U
BC
U
AB
U
CA
I
A
I
B
I
C
U
2
I
2
U
A
U
B
U
C
I
A
I
B
I
C
U
2
I
2
A
B
Figure 214: 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 397: Equations for calculating angle difference for positive-sequence quanti-
ty polarizing method
Faulted
phases
Used
fault
current
Used
polarizi
ng
voltage
Angle difference
A I
A
U
1
ANGLE A U I
A
RCA
_ ( ) ( )= − − ϕ ϕ ϕ
1
(Equation 22)
B I
B
U
1
ANGLE B U I
B
RCA
_ ( ) ( )= − − − ϕ ϕ ϕ
1
120
o
(Equation 23)
C I
C
U
1
ANGLE C U I
C
RCA
_ ( ) ( )= − − + ϕ ϕ ϕ
1
120
o
(Equation 24)
A - B I
A
-I
B
U
1
ANGLE A U I I
A B
RCA
_ ( ) ( )= − − − + ϕ ϕ ϕ
1
30
o
(Equation 25)
Table continues on the next page
1MRS759142 F Protection functions
REX640
Technical Manual
357