ABB COM600 series, User'S & Technical Manual, Page: 22 / 60

The fault distance calculation algorithm for the three-phase fault impedance loop is
defined by using the setting Load Com PP loops = "Disabled"/"Enabled" and setting
Simple mode PP loops = "Disabled"/"Enabled" setting.
The load compensation can be enabled or disabled with the Load Com PP loops =
FALSE/TRUE setting. The load compensation should be disabled only if the ratio between
the fault current and load current is large or when the value of the fault distance estimate
for the short circuit fault is required for each shot of an autoreclosing cycle.
The fault distance calculation is the most accurate when the calculation is made with the
fault loop model. This model requires positive sequence impedances as initial data. If
the data is not accessible, then the calculation can be made with a simple fault loop model
that does not need any impedance data. The simple fault loop model is enabled, with the
value Simple mode PP loops = TRUE. When the simple model is enabled, the conversion
of electrical fault distance into a physical distance is not done in the IED and the
FLT_DISTANCE output is not valid. The estimated impedances are still calculated and
shown normally in their respective outputs.
The function calculates XFPHASE, which is the positive sequence fault reactance in
primary ohms and is available as an output.
Table 4.3-1 Explanation of variations
Description Abbreviation
Estimated fault loop resistance in primary ohms RFLOOP
Estimated fault reactance in primary ohms XFLOOP
Positive sequence fault reactance in primary
ohms XFPHASE
Estimated fault resistance in primary ohms RF
Positive sequence resistance from the substa-
tion to the fault location R1
Positive sequence reactance from the substa-
tion to the fault location X1
Earth return path resistance from the substation
to the fault location = (R0 - R1)/3 RN
Earth return path reactance from the substation
to the fault location = (X0 - X1)/3 XN
Zero sequence resistance from the substation
to the fault location R0
Zero sequence reactance from the substation
to the fault location X0
Physical fault resistance at the fault location. In
case of earth faults, it includes the arc and the
earthing resistance. In case of the phase-to-
phase faults, it equals to the arc resistance
between the phases. In case of three-phase
faults, it equals to the arc resistance per phase. Rfault
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1MRS758734 COM600 series 5.1
Substation Analytics Technical Manual