ABSTRACT
Faults and sequence quantities can be visualized and perhaps better understood by several "helicopter" views in contrast to the specific representations and calculations. Accordingly, several overview "flights" are presented for the shunt faults, which are the most common occurring types. The collapse of voltage and increase of current for the four shunt faults are experienced in a power system. Faults cause instantaneous changes in the voltages and current. The voltages and currents that are generated by the sources can be only positive sequence by design—nothing else. For phase-to-phase faults negative sequence provides the necessary transition, with the unfaulted phase sequence currents in opposition to provide zero or low current. For phase-to-phase faults negative sequence provides the necessary transition, with the unfaulted phase sequence currents in opposition to provide zero or low current. Protection engineers automatically tend to think in its terms when evaluating and solving unbalanced situations in the power system.
