Arc-Flash 4800V

[Mike01]

On a 4800V system with 15Kv class gear when running a arc-flash study based on IEEE-1584-2002, the gap distance for 15Kv gear is 153mm as opposed to 102mm for 5Kv class gear, however when you run the serino of a 4800V system on 5Kv gear with 153mm gap distance the category increases 1 class in most cases why is this if the clearing time does not change and the available fault current remains the same??

 

[jim dungar]

On a 4800V system with 15Kv class gear when running a arc-flash study based on IEEE-1584-2002, the gap distance for 15Kv gear is 153mm as opposed to 102mm for 5Kv class gear, however when you run the serino of a 4800V system on 5Kv gear with 153mm gap distance the category increases 1 class in most cases why is this if the clearing time does not change and the available fault current remains the same??

The distance of the gap.

Just like in arc welding, with everything else constant the smaller the gap the more intense the arc.

 

[zog]

Zog say "Bigger ball of fire make more heat"

 

[bob]

On a 4800V system with 15Kv class gear when running a arc-flash study based on IEEE-1584-2002, the gap distance for 15Kv gear is 153mm as opposed to 102mm for 5Kv class gear, however when you run the serino of a 4800V system on 5Kv gear with 153mm gap distance the category increases 1 class in most cases why is this if the clearing time does not change and the available fault current remains the same??

Mike
Put your data up. I did it guessing at the info and the results were the same.
Eq. Class
Cond Gap
Work Dist
Avail 3 phase fault
Voltage
Arc Duration
Arc duration at reduced current
How are you getting the available 3 phse fault?