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 Post subject: Overhead switch arc gap
PostPosted: Thu Jul 09, 2009 3:46 pm 
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Joined: Wed Jun 24, 2009 4:45 pm
Posts: 41
Location: WA State
When using IEEE 1584 Table 4, does an overhead switch on a utility 12.47 kV distribution circuit fall under the open air category or the switchgear category?

I figure that open air is applicable and that switchgear is intended for enclosed type equipment, which this is not.


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PostPosted: Thu Jul 09, 2009 6:59 pm 
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Location: Charlotte, NC
If it is an open air break switch, then it shoud be analyized as open air.

Alan


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PostPosted: Thu Jul 09, 2009 7:02 pm 
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And if it is utility owned open air equipment, I would use Arcpro and not 1584 for the numbers.

Sorry for the double post.

Alan


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PostPosted: Fri Jul 10, 2009 4:56 pm 
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acobb wrote:
And if it is utility owned open air equipment, I would use Arcpro and not 1584 for the numbers.

Sorry for the double post.

Alan


Can you please explain why the preference for Arcpro?


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PostPosted: Sat Jul 11, 2009 5:58 am 
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The open air calcs for over 1000 volts in 1584 assume a 3 phase fault. The NESC treats everything as a single phase fault because of the larger phase spacings. Arcpro was used to create the tables in the NESC and models single phase arcs in open air. We only use 1584 for enclosures and voltages less than 1000 volts.


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PostPosted: Mon Jul 13, 2009 7:13 am 
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Great feedback, thank you very much!


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