Protection Planning and System Design to Reduce Arc Flash Incident Energy in a Multi-Voltage-Level Distribution System to 8 $hbox{cal/cm}^{2}$ (HRC 2) or Less—Part I: Methodology

摘要

The industry is heading toward innovations in the electrical system designs, equipment, and protection to limit the arc flash hazard. This paper demonstrates that, in a multi-voltage-level (medium and low voltages) distribution system, the incident energy can be reduced to 8 $hbox{cal/cm}^{2}$ or even less [hazard risk category 2] so that a personal protective equipment outfit that is greater than two is not required. This can be achieved with the current state-of-the-art equipment and protective devices. This paper has two parts: part 1 is for the methodology, and part 2 is for the analysis. There are variations in the calculation results, depending upon the calculation methods. A new method for the calculation of the energy accumulation to account for the decaying nature of the short-circuit currents is presented.