Electric Arc Behavior: Phase Angle ϕ-Orbits of I-V Evolution

Lissajous orbits of the current-voltage phase angles, are suggested to facilitate a synthetic study of fault current and particularly of arc current, predicting its behavior. In fact, an interval of self-extinguishing arc fault is marked in the plane of the elliptical orbits as edge between continuous and pulsating prospected behavior. The arc ignition introduces generally an asymmetry for the first half cycle of the invariant time evolutions. The arc current model is obtained as an extension of bolted short-circuit analysis: in a simplified approach the waveform of the arc voltage is limited to the fundamental harmonic. The simplified method, applicable with a system voltage either under 1000 V or higher 1000 V, allows to determine easily basic parameters, such as arc current RMS and peak values, conduction angle, arc power and arc energy.