RECLOSER CONTROL EVRC2A-N6,NT
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8.6. Fault Locator
The fault locator calculates the distance to the fault. When fault occurs the magnitude and the
phase of voltage and current are varied, and then fault type(phase to ground, (phase to phase to
ground), phase to phase, three phase) can be determined by the analysis of these variations, and
fault distance can be calculated by the estimation of the apparent impedance.
This calculation is based on the assumptions that the feeder positive and zero sequence
impedance are a constant per unit distance and fault impedance is composed of pure resistance.
In calculating, errors could be introduced by several reasons(fault resistance etc.), the major error
due to fault resistance can be reduced by comparing the prefault current and voltage to the fault
current and voltage.
For more accurate calculation, the prefault data is required at least 2 cycles, and the after fault
data is required at least 2 cycles.
If the line impedance per unit and total length were known, the fault distance can be easily
achieved, but source impedance is not required.
Fault data may not be accurate for a close-into-fault condition where there is no prefault power
flow.
In case of closing, during a reclose sequence, the apparent distance of the first fault is very useful.
The algorithm for the fault locator is most applicable to a radial three-phase feeder.
Faulted distribution system is considered as following simplified
“Figure 8-1. Faulted
distribution system circuit”
for example.
Figure 8-1. Faulted distribution system circuit
The calculated “Fault Location” can be checked on the “FAULT CYCLE” event menu. For more
details, refer to
“12.1. Waveform Capture”
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