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| TCC Creation https://brainfiller.com/arcflashforum/viewtopic.php?f=23&t=2793 |
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| Author: | Josh Gatlin [ Thu Jun 13, 2013 6:16 am ] |
| Post subject: | TCC Creation |
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"? |
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| Author: | AB P.E. [ Thu Jun 13, 2013 6:43 am ] |
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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. |
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| Author: | Josh Gatlin [ Thu Jun 13, 2013 6:49 am ] |
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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. |
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| Author: | Bruce Moore [ Mon Jun 17, 2013 5:01 am ] |
| Post subject: | |
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.
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| Author: | wbd [ Tue Jun 18, 2013 4:25 am ] |
| Post subject: | |
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. |
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| Author: | JohnnyT [ Mon Jul 15, 2013 10:02 am ] |
| Post subject: | |
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. |
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