It is currently Mon Aug 03, 2020 11:27 pm



Post new topic Reply to topic
Author Message
ekstra   ara
 Post subject: 208V low arc current long clearing time
PostPosted: Thu May 27, 2010 9:12 am 

Joined: Thu May 13, 2010 1:01 pm
Posts: 1
Location: Duncan SC
I am reviewing an arc flash study with several low voltage (208) panelboards that have a low calculated arc current, less than 3000A, with long clearing times, 2 seconds or more. This is resulting in high energy and Cat #3 or #4 PPE. Are these calculations reasonable? Will that low a voltage and current even sustain an arc? Most of these currents are below the current calculated from a 112.5 kVA transformer which can be ignored at 208V. Any thoughts would be appreciated.

Thanks


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Fri May 28, 2010 3:31 am 
Plasma Level
User avatar

Joined: Mon Sep 17, 2007 5:00 pm
Posts: 1498
Location: Scottsdale, Arizona
You will find numerous posts about this on the forum. Here is a short summary:

The "less than 125 kVA" limit was initally used in IEEE 1584. Later, a few concerns arose about its validity. A few people (I'm one of them) have been involved in testing.

It looks like eventually the cut off will be based on short circuit current not kVA and from what I have been involved with it will be much lower than the current from a 112.5 kVA transformer.

I am now the task group leader for this with IEEE 1584 and it is formally being reviewed.

You will find more detail throughout the forum.

Good Luck, Let me know if you have any more questions.

_________________
Jim Phillips, P.E.
Brainfiller.com


Top
 Profile Send private message  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 2 posts ] 

All times are UTC - 7 hours


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:  
cron
© 2019 Arcflash Forum / Brainfiller, Inc. | P.O. Box 12024 | Scottsdale, AZ 85267 USA | 800-874-8883