Generalized Model for Analyzing the ARC Fault Currents in A.C. &D.C.

Abstract

The IEEE1584-2018 guide is the universally recognized method to evaluate the arc-flash phenomenon. Previous works introduced the Parise model, a simplified approach that outlines the behavior of the arcing fault current as an extension of the bolted fault analysis highlighting that in a.c. a necessary parameter is the power factor PF of the bolted short-circuit. This method considers values in p.u. of the currents normalized in relation to the bolted short-circuit value. In this way it allows to compile a complete map of the arc fault current i_k in p.u. assuming as known a value of the characteristic arc current i_arc in p.u. and considering the values of PF variable in the complete theoretical range from 1 to 0. Then, it is generalized as it allows analyzing the behaviors of active powers of the complete circuit, only based on the normalized parameters i_k, i_arc and on the PFs. Adopting this approach, it is possible to calculate the arc resistance in a deductive manner knowing the arc fault current calculated in compliance to the IEEE Guide and the bolted short-circuit current. In order to evaluate the incidence of the power factor on the values of the arc current and so on the arc resistance, this model allows to calculate the prospected entities of variations considering assigned range of PF in relation to the bolted short-circuit PF.