It is currently Mon Dec 11, 2017 4:11 am



Post new topic Reply to topic
Author Message
ekstra   ara
 Post subject: 1/2 cycle vs 1.5 to 4 cycle option
PostPosted: Wed Dec 02, 2009 7:27 am 
Offline

Joined: Wed Dec 02, 2009 7:24 am
Posts: 2
Any thoughts on using the 1.5 to 4 cycle fault contributions vs the 1/2 cycle?


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Wed Dec 02, 2009 7:38 am 
Offline
Sparks Level

Joined: Thu Jul 19, 2007 7:54 am
Posts: 201
Location: St. Louis, MO
I have wondered a little about this myself. What is the correct fault duty to use for the short circuit calculation when doing arc flash studies?

I can tell you that when I started doing arc flash studies, we used ETAP to do the short circuit study, but had to do the arc flash calc using the IEEE spreadsheet, and calculate the trip time using TCC's, I was told to use the 1.5-4 cycle calculation in ETAP. I'm not sure what the reasoning was behind it, though, except that this may have produced a better (more realistic) current level by which to find trip times.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Wed Dec 02, 2009 7:48 am 
Offline

Joined: Wed Dec 02, 2009 7:24 am
Posts: 2
In the help file for the Acr Flash Case parameters it says, "If this option is selected, the module will use the symmetrical 1.5 to 4 cycle 3-phase (interrupting) fault current to determine the fault clearing time and the incident energy for medium voltage elements (above 1.0 kV)."

Note the above 1000V. Does this mean that for medium voltages less than 1000V (480V & 600V) we should use the 1/2 cycle?


Top
 Profile Send private message  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 3 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