Power Factor Relevance on Arc Flash A.C

This paper upgrades a method, proposed to calculate the incident energy and the arc-flash boundary in a previous paper, and introduces a simplified calculation of the arc fault current. The approximated method, proposed as complementary to the method of the IEEE 1584–2018 guide, aims to have a physical understanding of the phenomenon and adopts factors to analyze singularly the various parameters of influence related to the effective value of the bolted short-circuit current, the nominal voltage of the electrical system, the configuration and gap of the electrodes. The results obtained with the proposed approximate calculation are completely comparable with the results obtained with the IEEE 1584–2018 guide, confirming the validity of introduced factors and equations. This paper deals particularly with the relevance of the power factor of the bolted short circuit current in the characterization of the arc fault, the arc voltage value, the arc current and its behavior, continuous or pulsating. Therefore, the knowledge of the arc fault current and of the power factor, which the IEEE 1584 guide does not consider, allows to easily evaluate the operational value of the arc resistance.

I. Introduction

The guide IEEE1584-2018 [1] assess the risk of Arc Flash and presents the Arc-Flash Hazard Calculations with an empirical model interpolating intermediate values of average arc current, incident energy, and arc-flash boundary.