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Question about table 410-2 ieee.c2. vs arcpro https://brainfiller.com/arcflashforum/viewtopic.php?f=4&t=4603	Page 1 of 1

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Author:	Jensaugust12 [ Thu Mar 15, 2018 2:02 am ]
Post subject:	Question about table 410-2 ieee.c2. vs arcpro
For my understanding of this tables: It is used some kind of distance from arc:"Calculated by using minimum approach from Table 441-2 and subtracting two times the assumed arc gap length" Does this mean that for instance the 161 to 169 kV calculation is done wirth the following input: Ik= 20kA(assumed single phase) Arc Gap distance 161kV/10=16.1 inch Distance to gap: (From table 441-2): 51 inches(10ft3inch,use T=3)-2*16.1 inches=19 inches If I do calculation with arcpro(is was told that this tables where made by using arcpro?), input shown in picture. I get a result of 11.9 cal/cm2 and not 4cal Attachments: c2picture.JPG [ 14.37 KiB | Viewed 1331 times ] arcpro_quest.JPG [ 26.45 KiB | Viewed 1331 times ]

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Author:	stevenal [ Thu Mar 15, 2018 8:27 am ]
Post subject:	Re: Question about table 410-2 ieee.c2. vs arcpro
The table uses line to line voltage, but when finding arc length the note 1 says to divide the line to ground kV by 10. Your calculated arc gap should be divided by sqrt(3). When I've looked at this in the past, I found the tables did not necessarily correspond to the MADs in the same revision of the NESC. Looking back a revision or two produced better results. Why 9.3 cycles? Tabulated value is 11.9. Might try changing the electrodes; I forget which gave better results.

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