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 Post subject: DC Arc Flash Calculation for Arc Flash BoundaryPosted: Thu Jan 17, 2019 3:39 pm

Joined: Mon Aug 25, 2014 3:11 pm
Posts: 2
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?

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 Post subject: Re: DC Arc Flash Calculation for Arc Flash BoundaryPosted: Thu Jan 17, 2019 3:43 pm

Joined: Mon Aug 25, 2014 3:11 pm
Posts: 2
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.

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 Post subject: Re: DC Arc Flash Calculation for Arc Flash BoundaryPosted: Fri Jan 18, 2019 5:30 pm
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Joined: Tue Oct 26, 2010 9:08 am
Posts: 2174
Location: North Carolina
rlorenz2 wrote:
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?

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

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 Post subject: Re: DC Arc Flash Calculation for Arc Flash BoundaryPosted: Fri Aug 02, 2019 10:50 am

Joined: Tue Mar 05, 2019 5:47 am
Posts: 10
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

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