SIGRA_MANUAL_B1_EN.pdf

Fault locator measurement of the distance to a fault

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Fault Locator Measurement of the distance to a fault in the event of a short circuit is a valuable addition to the functionality of the protection device. Fast locating of a fault can increase the line availability for the power-transmission system. 5.15.1 Functional Description General The fault locator is an independent and autonomous funtion. The function allows the precise location of faults even on mixed line sections by using the line data entered. SIGRA also allows the two-ended fault location (op- tional), which significantly improves fault-location determination, especially for lines with infeed from both line ends, load flow, faults involving ground or faults with high resistance. You can use the single-ended fault location in any case. If data for the remote end of the line are also available, then use the two-ended fault location. 3 fault locations are calculated in total: 1 calculated by two-ended fault location 2 calculated by single-ended fault location (one from each end) In the case of a single-ended fault location, the measured/calculated ground current from a selectable node is taken into account for the calculation of the parallel-line compensation. Usually, the two-ended fault location is more robust than the single-ended fault location, as the result of the two- ended fault location is independent from the zero-sequence component, the residual compensation factor or the parallel line mutual coupling. Especially the residual compensation factor is difficult to determine in practice. As it is inhomogeneous over the line, it causes inaccuracies in the single-ended fault location calculations. However, for high-current faults in the close vicinity of one end of the line, the single-ended fault location is more reliable. The transmission line can be inhomogeneous. It can be split into several sections for the calculation, for exam- ple, a short cable followed by an overhead line. For such configurations, the line sections can be parameterized individually. The fault locator converts measuring errors, line symmetry, and geometry based on the known voltage profile of the line into a variation in distance. With the variation in distance, the fault locator can decide whether to perform the two-ended fault location or not. If this variation in distance is great, in relation to the line section, then the result of the two-ended fault location is rejected. Only the single-ended fault location is displayed. The calculated accuracy is reported on a scale from 0 to 10 with increasing accuracy. Double ground faults with different base points, source-side faults, and faults which are not on the line between the 2 measuring points are only calculated and displayed using the single-ended fault location.
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  • Fall '19
  • Sigra

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