#3 Arc Flash - Project Example (after event)

Webinar #3 Arc Flash - Project Example?

Short summary from my side. Excellent questions in Q&A session where I pick 3 and included it below in this article. I see that end of webinar recording was cut at the end but to be honest I have no idea why it happen. Most likely we reached 60 min meeting time limit ??

Let me know in comments:

? Will it be better if I will create mailing list so everyone can sign in for upcoming webinars updates ?

?? link to YouTube recording >>> https://youtu.be/Ahh_CoGkaiE

? Q&A session :

All questions were answered during live session. Interesting questions below:

Q1:Do you consider MV switchgear Internal Arc Classification (e.g. AFLR) in your arc flash assessment for PPE?

A1:Yes. It is included and verified if IAC rating is in range of current and time eg. 16kA/1sec vs calculated 12kA and 0,8sec. It might be as well 1.2sec and will be not OK.

Q2: [14:46]Does your model take into account the current limiting effect through the fuses?

A2: No it is not. Officially IEC60909 and ANSI as well doesn't allow to use current limiting effect in short circuit calculations. You need to show results as it is however than you can use it to select equipment including current limiting effect. It is two step process.

Q3:As I see the example was calculated according NFPA code. Is also a calculation according ISSA possible?

A3: Yes it is. NFPA70E refers to IEEE1584 in most of project and I assume by ISSA guide you refer to DGUV203-077 (box method calculation). In practice DGUV is theoretical method (background test at least are not given) and from my last experience it is much more conservative in results. In last project I calculate results for the same system with both methods and DGUV outcome was more conservative (lot of locations were above APC2 so no PPE available) than IEEE1584.