DC Arc flash calculations for solar farms

Abstract

The NFPA 70E standard - 2012 edition and the CSA Z462-12 standard describe the calculations required to determine the approximated incident energy in a DC arc flash. These calculations assume that the power source for the DC system is linear. This paper describes the calculations required to estimate the incident energy in a DC arc flash for solar farms, where the power source is highly nonlinear. The equations required for the calculation are derived from fundamentals and compared to the equations provided by the above standards. The incident energy levels found in a typical solar farm are presented in an example, where the results obtained by the application of the standards and the proposed method are compared. Recommendations to include in the standards the provisions for the calculation of DC arc flash in solar farms are given in this paper.