I am preforming DC arc flash calculations for a system with a reactor having the following ratings: 250VDC, 1000A, 262.5KVA, and 4.05%Z. I have calculated the incident energy using NFPA 70E-2015 Section D.5 for the Maximum Power Method and looking to find the Arc Flash Boundary. Is it acceptable to use the Ralph Lee Calculation Method equation D.2.1(d) or (e) for determining the distance?, if so what "t" (time of arc exposure) would be used?

Thanks in advance.

I have found the linked spread sheet below online with AFB calculated, but because it is locked I cannot see the equation used. Based on using the Ralph Lee Method for my calculations I cannot come to the same conclusions as the spread sheet.

http://efcog.org/wp-content/uploads/2016/11/DC-Arc-Flash-Calculator-EFCOG-ESW-DC-SC.xlsx

Shouldn't be that hard since its basically a linear equation except for the D^2 term. Did you try solving it directly yourself?

I will reuse this topic.

Has anyone did DC arc flash for MV systems eg.rail 3kV ? I found only J.C.Das publication where he use S-O equations and I think at the end it was stated that it can be extended with reasonable results. I think S-O doesn't specify voltage limits for model but testing was done max at 1000VDC ( or 1200VDC).

I haven't seen this in any software yet
Any updates on this ?