ABB RER615 - Page 244

Self-polarizing as polarizing method
Table 260: Equations for calculating angle difference for self-polarizing method
Faulted
phases
Used
fault
current
Used
polarizing
voltage
Angle difference
A I
A
U
A
ANGLE A U I
A
A
RCA
_ ( ) - ( ) - = ϕ ϕ ϕ
B I
B
U
B
ANGLE B U I
B
B
RCA
_ ( ) - ( ) - = ϕ ϕ ϕ
C I
C
U
C
ANGLE C U I
C
C
RCA
_ ( ) - ( ) - = ϕ ϕ ϕ
A - B I
A
- I
B
U
AB
ANGLE A U I I
AB
A B
RCA
_ ( ) - ( - ) - = ϕ ϕ ϕ
B - C I
B
- I
C
U
BC
ANGLE B U I I
BC
B C
RCA
_ ( ) - ( - ) - = ϕ ϕ ϕ
C - A I
C
- I
A
U
CA
ANGLE C U I I
CA
C A
RCA
_ ( ) - ( - ) - = ϕ ϕ ϕ
In an example case of the phasors in a single-phase earth fault where the faulted
phase is phase A, the angle difference between the polarizing quantity U
A
and
operating quantity I
A
is marked as φ. In the self-polarization method, there is no
need to rotate the polarizing quantity.
Figure 124: Single-phase earth fault, phase A
In an example case of a two-phase short-circuit failure where the fault is between
phases B and C, the angle difference is measured between the polarizing quantity U
BC
and operating quantity I
B
- I
C
in the self-polarizing method.
Protection functions
1MRS758755 C
244 REC615 & RER615
Technical Manual