Fault loops “AG Fault” or “BG Fault” or “CG Fault”
Fault loops “AG Fault”, “BG Fault” or “CG Fault” are used for single-phase-to-earth
faults. When the individual earth faults are located at different feeders, they are also
applied in the case of two-phase-to-earth fault. In this case, the phase-to-earth loop
(either “AG Fault” or “BG Fault” or “CG Fault”) corresponding to the faulty phase at
the protected feeder, is used for calculation.
Figure 250 shows the phase-to-earth fault
loop model. The following impedances are measured and stored in the recorded data
of SCEFRFLO.
Flt point resistance R
fault
=
GUID-2503378E-4AC5-4E9F-9D77-2E7C71592C37 V3 EN (Equation 46)
Flt loop resistance R R R
N fault
= + +
1
GUID-4DF67AFC-67E4-4BCB-958E-CC9E4872E252 V3 EN (Equation 47)
Flt loop reactance X X
N
= +
1
GUID-B4E21936-B993-4A8A-9C4A-7425F8AC4670 V3 EN (Equation 48)
GUID-56EC16DD-7F6A-4DE5-935E-4302196DE21A V3 EN (Equation 49)
R
1
Estimated positive-sequence resistance from the substation to the fault location
X
1
Estimated positive-sequence reactance from the substation to the fault location
R
0
Estimated zero-sequence resistance from the substation to the fault location
X
0
Estimated zero-sequence reactance from the substation to the fault location
R
N
Estimated the earth return path resistance (= (R0 – R1)/3) from the substation to
the fault location
X
N
Estimated is the earth return path reactance (= (X0 – X1)/3) from the substation to
the fault
R
fault
Estimated fault resistance at the fault location
The recorded data Flt phase reactance provides the estimated positive-sequence
reactance from the substation to the fault location.
1MRS758755 A Section 5
Protection related functions
REC615 and RER615 485
Technical Manual
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