It is currently Wed Aug 05, 2020 7:35 am



Post new topic Reply to topic
Author Message
ekstra   ara
 Post subject: TCC Creation
PostPosted: Thu Jun 13, 2013 6:16 am 

Joined: Tue Mar 12, 2013 12:31 pm
Posts: 14
Location: Dallas, TX
Just hoping somebody can point me in the right direction as far as where to find some Arc Flash information. I am a new EE working on Arc Flash for a few months now. I am to the point where my system is modeled but I am unsure what/how you choose the equipment for each TCC so you have the system fully accounted for in the "TCC/ One line -system's existing settings" section. Where can I go to read up on "what to model" instead of "how to model"?


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Thu Jun 13, 2013 6:43 am 
Sparks Level

Joined: Wed Jun 02, 2010 12:59 pm
Posts: 70
Location: Milwaukee WI
I suggest our esteemed forum sponsor's book:
"Complete guide to Arc Flash Hazard Calculation Studies"
Chapter 9 title: "Arc Flash Duration and Time Current Curves".
My copy was purchased from Amazon.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Thu Jun 13, 2013 6:49 am 

Joined: Tue Mar 12, 2013 12:31 pm
Posts: 14
Location: Dallas, TX
AB P.E. wrote:
I suggest our esteemed forum sponsor's book:
"Complete guide to Arc Flash Hazard Calculation Studies"
Chapter 9 title: "Arc Flash Duration and Time Current Curves".
My copy was purchased from Amazon.


Thanks, I already have it in the shopping cart. However, in the mean time I think I may have found a general guide on SKM's website that I didn't come across before. I can't post the link since I am a new member however it is skmdotcom/powersystemspecs. I believe this may help with some more general "all my bases are covered" questions I have.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Mon Jun 17, 2013 5:01 am 

Joined: Mon Apr 22, 2013 12:35 pm
Posts: 1
Location: Kansas City, Mo
Josh Gatlin wrote:
Just hoping somebody can point me in the right direction as far as where to find some Arc Flash information. I am a new EE working on Arc Flash for a few months now. I am to the point where my system is modeled but I am unsure what/how you choose the equipment for each TCC so you have the system fully accounted for in the "TCC/ One line -system's existing settings" section. Where can I go to read up on "what to model" instead of "how to model"?
Josh, I work for a firm that specializes in Arc Flash. Our in-house EE has use use the basis of one level below any 400 Amp device and we fequently go two. I hope this will help you in your quest.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Tue Jun 18, 2013 4:25 am 
Plasma Level
User avatar

Joined: Wed May 07, 2008 5:00 pm
Posts: 822
Location: Rutland, VT
Let's not mix up arc flash with coordination and selectivity which the TCCs are used for. Typically, one would start from the bottom and work up (bottom here is the farthest away from incoming power feed so typically at the bottom of the one-line).
Usually one will choose the largest 2 or 3 protective devices plus the main feed device to include on the TCC. I will also look at a radial feed to a transformer with a panel (ie 480V bkr feeding a transformer (480-120/208V) to look at inrush current and bkr setting)
Building a set of TCCs will allow one to determine the coordination of the system devices. This is important as many times making an adjustment to improve the arc flash hazard will adversely affect the coordination and selectivity of the system.

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


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Mon Jul 15, 2013 10:02 am 

Joined: Fri Sep 10, 2010 7:48 pm
Posts: 17
Location: Idaho
Josh, the two primary factors that go into an arc flash study are available fault current and fault duration or fault clearing time. When modeling there are several items that affect these factors. In regards to the fault current, you will need to model the source, distribution (including transformer - ratings (impedance, size, configuration, grounding, taps, etc), overhead lines, cables, switchgear, MCCs, (include brace ratings, continuous current, phase spacing, etc.). For the fault clearing time you will need to include all of the protection for the circuits modeled, which will also need to include the break response time to open upon a command from the relay. You will also need some motor information for those larger inertia loads that will provide additional fault contributions.

Basically you are going to need a very comprehensive model of the electrical system that is capable of doing fault studies and relay coordination. Once you have this modeled you will have enough information to work on Arc Flash Studies.


Top
 Profile Send private message  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 6 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:  
© 2019 Arcflash Forum / Brainfiller, Inc. | P.O. Box 12024 | Scottsdale, AZ 85267 USA | 800-874-8883