Simplified arc-fault model: the gearing pace model

The paper refers to recently published arc models defining the arc voltage and the arc current. It is generally recognized that the arc-fault impedance is a resistance and the arc current contains harmonics; therefore, the resulting fault impedance has a larger magnitude and a power factor much closer to unity than a short circuit in the bolted-fault circuit. To simplify past approaches of arc modeling, this work suggests considering the arc current as the fundamental harmonic. The arc voltage is modeled as a RMS voltage, Va, across a pure resistance; in this paper, the RMS arc voltage is defined as a function of gap width and bolted-fault current. The arc resistance and phase angle of the arc-fault circuit can be determined when the RMS arc voltage and the bolted-fault circuit impedance values are known. The behavior of the arc current is obtainable as an extension of bolted short-circuit analysis. Like a soldier has to gear the pace if by chance he introduces himself in the marching troupe, so he solves jumping or rubbing the feet, analogously the fault current does the same. With this approach, the behavior of the arc fault can be easily understood and the arc fault parameters such as conduction angle, peak value, and decreasing-to-zero value can be easily evaluated.