Improved method for arc flash hazard analysis

Abstract

Conventional arc flash hazard calculators use simple formulae to calculate the flash protection boundary and the incident energy density, but these methods do not represent the effects of the power supply system correctly. A new method is described which models the transient response of a 3-phase power system and its interaction with an arcing fault. The operation of current-limiting fuses in the time domain, and the focusing effect of the equipment enclosure are also considered.

DC arc flash calculations — Arc-in-open-air & arc-in-a-box — Using a simplified approach (Multiplication factor method)

“…Using Figures 4 and 5 in R. Wilkins [2], it is possible to estimate the values of a and k, and therefore also of A in for box sizes other than those specified in IEEE 1584 TM . This can also be done by using Figures 1 and 2 below which are similar to Figures 4 and 5 in R. Wilkins [2]. R. Wilkins [2] developed the optimum values of k and a as the values, which gave the least-squares best fit to the test data.…”

“…The values of a were determined by R. Wilkins [2] and are given in Table A Wilkins [2]: Table A-I in Appendix A gives the optimum values of a and k that were determined by R. Wilkins [2] for the three specific classes of equipment in IEEE 1584 TM , and they are related to the dimensions of the boxes used to represent the specific equipment classes. Using Figures 4 and 5 in R. Wilkins [2], it is possible to estimate the values of a and k, and therefore also of A in for box sizes other than those specified in IEEE 1584 TM . This can also be done by using Figures 1 and 2 below which are similar to Figures 4 and 5 in R. Wilkins [2].…”

“…The method is based on the assumption that the spherical energy density IE oa can be increased to a value of IE b to account for the additional reflected heat radiation from a box situation and that IE b /IE oa equals a multiplying factor M f for correcting from the energy density for an arc-in-openair situation to an arc-in-a-box situation, based on a simplified equation or methodology. A similar method was developed by R. Wilkins [2] and furthered by R. F. Ammerman, et al [3]. Equations provided here for determining the multiplying factor were derived from Equations 5 and 6 developed by R. Wilkins [2].…”

“…A similar method was developed by R. Wilkins [2] and furthered by R. F. Ammerman, et al [3]. Equations provided here for determining the multiplying factor were derived from Equations 5 and 6 developed by R. Wilkins [2].…”

“…Following is a method for calculating the incident energy and the arc flash boundary (AFB) distance for dc systems using the dc maximum power method as developed by D. R. Doan [1] and a multiplying factor method as developed by R. Wilkins [2] and furthered by R. F. Ammerman, et al [3] in lieu of the use of distance exponents. The method is based on the assumption that the spherical energy density IE oa can be increased to a value of IE b to account for the additional reflected heat radiation from a box situation and that IE b /IE oa equals a multiplying factor M f for correcting from the energy density for an arc-in-openair situation to an arc-in-a-box situation, based on a simplified equation or methodology.…”