ABB RELION Series Technical Manual page 240

Section 4
Protection functions
234
faulted phase is phase A. The polarizing quantity is rotated with 90 degrees. The
characteristic angle is assumed to be ~ 0 degrees.
GUID-6C7D1317-89C4-44BE-A1EB-69BC75863474 V1 EN
Figure 127: 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 and operating quantity I
AB
- I marked as φ.
B C
1MRS758755 A
REC615 and RER615
Technical Manual