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 210: 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 211: Two-phase short circuit, short circuit is between phases B and C
1MRS759142 F
Protection functions
REX640
Technical Manual
353
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