Hello:

I am currently working through a short circuit analysis and I have a few questions on how to approach analyzing DC Power Supplies:

1. Is there any guidance out there for analyzing DC Power Supplies (e.g., Input 480VAC with an output of up to 1000 VDC) that anyone knows of?

2. For the purposes of the short circuit analysis, are DC Power Supplies assumed to be capable of full power output with essentially no losses at the time of the short circuit similar to AC transformers? Are there any other considerations?

3. Can current limiting capability internal to the DC Power Supply be credited for limiting the current during a short circuit (thinking about downsteam sources and their available short circuit current)? It seems possible that with the high switching frequencies used to drive SCRs and fast sampling rate for feedback would be able to limit the short circuit current faster than the normal protective devices tripping (e.g., breaker, fuse, etc). Does anyone know of any documented discussion on this?

Thank you,

Steve

I took the arc flash training and for DC it appears to boil down to the maximum power method used by NFPA 70E or some derivation of various technical papers as described in this page: https://brainfiller.com/electrical-safe ... culations/

One followup question is: How do you quantify currently contribution from capacitors in a DC circuit if they are sufficiently large? Would the developed formulas for DC arc flash encompass capacitor current contribution or would this be separately calculated?