Basler BE1-11g Instruction Manual page 228

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To perform the actual distance calculation, the BE1-11g first must determine the faulted phase. Faults can
be categorized depending on the lines faulted. The various categories are LLL, LL, LLG, or LG where
L = line and G = ground.
To determine the faulted phase, the fault vectors are compensated for load flow using the pre-fault data.
Next, the compensated vectors are run through a series of sequence component comparisons. Once the
faulted phase is determined, the fault data along with the line parameters are applied using the Takagi
algorithm to determine the impedance of the faulted line. The impedance is divided by the impedance per
unit length to determine the distance to fault. This method assumes the line is homogenous and that the
line parameters do not change over the length specified. For a non-homogenous line, the distance would
need to be manually corrected.
The distance-to-fault results are limited to ±300% of the specified line length. This limit prevents
erroneous results from being displayed for non-overcurrent type faults, such as over or undervoltage
faults. A computed value greater than maximum line length is reported as n/a (not applicable).
Fault Reporting BE1-11g