Entec ETMFC610, Руководство пользователя, Страница: 310 / 372

Multi-Function Control ETMFC610 http://www.entecene.co.kr
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8.5.10. 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.
The algorithm for the fault locator is most applicable to a radial three-phase feeder.
Faulted distribution system is considered as following simplified
“Figure 8-36. Faulted
distribution system circuit” for example.
Figure 8-52. Faulted distribution system circuit
The calculated “Fault Location” information be checked on the “Fault Cycle” event menu. For
more details, refer to
“9.2. Fault Event” and “9.3. Fault Cycle - Summary” .
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