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 Post subject: Arc Flash in High Altitude Applications
PostPosted: Fri Feb 19, 2010 9:14 am 
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Joined: Fri Feb 19, 2010 8:59 am
Posts: 2
Location: Charlottesville, VA
What impact would lower rH and quite high altitudes have on hazard distances and arc flash hazards in general? We are working on a 23 kV transmission system at 5000 meters in the Andes Mountains.


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PostPosted: Fri Feb 19, 2010 10:20 am 
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Joined: Thu Feb 11, 2010 5:51 pm
Posts: 22
Location: Great White North
At higher altitudes the voltage stress will definetly cause the air to electrically break down sooner at a lower voltage level(approx.2-10%).(google for these actual correction values/formula) :)


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PostPosted: Fri Feb 19, 2010 11:39 am 
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Joined: Fri Feb 19, 2010 8:59 am
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Location: Charlottesville, VA
Thanks for the info. I have been Googling around but an having trouble finding definitive info as to how much impact it might have. Will keep looking.


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PostPosted: Fri Feb 19, 2010 2:14 pm 
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Joined: Thu Feb 11, 2010 5:51 pm
Posts: 22
Location: Great White North
Try this link:


http://ieeexplore.ieee.org/Xplore/login.jsp?url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F6616%2F17682%2F00816711.pdf%3Farnumber%3D816711&authDecision=-203


Study of the breakdown voltage of the air in high altitudes, applying lightning impulses (1.2/50 ╬╝s) under conditions of controlled humidity and temperature


Note:You will need to be a I.E.E.E. member

I will try to get the sphere gap graphs for you.

:)


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PostPosted: Fri Feb 19, 2010 4:09 pm 
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Joined: Thu Feb 11, 2010 5:51 pm
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Location: Great White North
Here is a link to these spark gap correction factors for humidity and altitude(it is the 4th one down on this list).Enjoy (: )


http://www.google.ca/search?sourceid=navclient&ie=UTF-8&rlz=1T4RNWE_enCA309CA309&q=sphere+gaps+correction+factors


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