ABB Relion 620 Series - Page 282

Figure 138: 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.
Figure 139: Two-phase short circuit, short circuit is between phases B and C
Protection functions
1MRS757644 H
282 620 series
Technical Manual