DETECTING ARCING DOWNED-WIRES USING FAULT CURRENT FLICKER AND HALF-CYCLE ASYMMETRY

The downed-wires problem, known as high impedance faults, is described . A high voltage laboratory setup was devised to investigate the pheno menon. The laboratory model results agreed with field test results, an d previous research efforts. The arcing fault model was justified. The setup was used as a source of fault current signal. A simple approach was taken to design an arcing fault detector. The algorithm utilizes the random behavior of the fault current. It compares the positive and negative current peaks in one cycle to those in the next cycle to mea sure the flicker in the current signal. The asymmetry of the current i s calculated by comparing-the positive peak to the negative peak, for each cycle; the moving window length is half a cycle. Both values are used as a signature of arcing. The result is filtered and compared wit h a suitable detection threshold. The algorithm was tested by traces o f normal load, and no-load current disturbed by currents of faults on dry and wet soil, are welders, computers, and fluorescent light loads, as well as short circuit currents. The algorithm performed well under the test conditions, except for the are welder load. This load is als o a source of insecurity for other algorithms. The detection criterion will be integrated with another detection method to improve the secur ity during arcing load events.