It is currently Wed Feb 21, 2018 6:16 pm



Post new topic Reply to topic
Author Message
ekstra   ara
 Post subject: 3 phase fault
PostPosted: Tue Jun 28, 2011 10:57 am 
Offline

Joined: Wed Jun 08, 2011 10:52 am
Posts: 16
for arc flash analysis, we calculate arcing current based on 3 phase bolted current. what if i wanna calculate arc boundary or incident energy on one phase equipment? do u have to still use 3 phase fault current?

other question is for arc short circuit current, voltage has to be taken into account. this voltage is line to ground or line to line?

pls let me know, i will be appreciated that

jim


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Tue Jun 28, 2011 7:15 pm 
Offline
Arc Level

Joined: Mon Jan 18, 2010 11:35 am
Posts: 445
Location: Wisconsin
cooldesign wrote:
for arc flash analysis, we calculate arcing current based on 3 phase bolted current. what if i wanna calculate arc boundary or incident energy on one phase equipment? do u have to still use 3 phase fault current?

You need to use some other methodology other than simply IEEE1584. There is no single industry accepted method. Your company should evaluate all of the possible options and then adopt one which it is willing to defend before a judge and jury.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Wed Jun 29, 2011 7:01 am 
Offline

Joined: Wed Jun 08, 2011 10:52 am
Posts: 16
what is the other methology? what i am trying to ask you, do we do arc flash for one phase equipment? i calculated all 3 phase faults, but i did not calculate one phase fault for single phase lines. do i have to calculate single phase faults currents for arc flash? because i saw in the IEEE1584 starndart, it says arc flash analysis will be done for 3 phase analysis because it is greater than one phase fault current. what if for one phase equpment?


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Wed Jun 29, 2011 9:26 am 
Offline
Plasma Level
User avatar

Joined: Wed May 07, 2008 5:00 pm
Posts: 711
Location: Rutland, VT
The most conservative approach is to use the 3 phase values for the single phase equipment.

_________________
Barry Donovan, P.E.
www.workplacesafetysolutions.com


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Wed Jun 29, 2011 9:34 am 
Offline
Arc Level

Joined: Mon Jan 18, 2010 11:35 am
Posts: 445
Location: Wisconsin
wbd wrote:
The most conservative approach is to use the 3 phase values for the single phase equipment.


To you have a reference for that statement?

Isn't the most conservative approach is to assume no PPE is available, therefore "live" work is prohibited?


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Wed Jun 29, 2011 9:57 am 
Offline

Joined: Wed Jun 08, 2011 10:52 am
Posts: 16
so, if it is single phase cable or equipment. we need to cut energy off then work for that equipment?

or even if it is single phase, we can use the 3phase fault current?


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Wed Jun 29, 2011 10:06 am 
Offline
Sparks Level

Joined: Wed May 13, 2009 3:19 pm
Posts: 56
cooldesign wrote:
for arc flash analysis, we calculate arcing current based on 3 phase bolted current.


What kVA, fault level, and voltage are you talking about here?


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Wed Jun 29, 2011 10:23 am 
Offline

Joined: Wed Jun 08, 2011 10:52 am
Posts: 16
i have some 25kva one phase transformers, i am getting 3 phase fault currents around 800 amps, voltage level is 240 volts


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Wed Jun 29, 2011 6:12 pm 
Offline
Arc Level

Joined: Mon Jan 18, 2010 11:35 am
Posts: 445
Location: Wisconsin
cooldesign wrote:
i have some 25kva one phase transformers, i am getting 3 phase fault currents around 800 amps, voltage level is 240 volts


I believe the accuracy/reliabilty of IEEE1584 falls off around 750A of arcing fault current.


Top
 Profile Send private message  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 9 posts ] 

All times are UTC - 7 hours


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
© 2017 Arcflash Forum / Brainfiller, Inc. | P.O. Box 12024 | Scottsdale, AZ 85267 USA | 800-874-8883