Arc flash hazard calculations in L-V & M-V DC systems-part i-short-circuit calculations

IEEE 1584 Guide does not address arc flash hazard in DC systems. The interest in this subject is evidenced by current publications. NFPA 2012 has added a small description of the calculations of arc flash hazard in dc systems. However, there are serious inaccuracies in the application of the methodology advocated in NFPA. A review of the current literature indicates that there is no comprehensive document on the subject and some of the assumptions made in the current literature are not accurate, for example, with respect to short-circuit current profiles and protective devices in DC systems; which are very fundamental to the accurate calculations of arc flash hazard in the dc systems. The paper is presented in two parts. This first part provides equations with practical examples of short-circuit calculations in dc systems. The second part provides analysis of arc flash hazard. Accurate calculations of the short-circuit currents and ascertaining their profiles is the first step in the arc flash hazard analysis.