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 Post subject: If system configurations change when do you relabel?
PostPosted: Wed May 04, 2011 8:19 pm 

Joined: Tue Mar 02, 2010 1:50 pm
Posts: 26
Hi,
I was working on arc flash labels for a wind site. We are labeling 87 turbines with possibly 20 labels per turbine, which equals a ton of labels. My question is, supposing another collector is added to the site and changes the available fault current to each turbine. The fault current at each bus would slightly change, and thus the incident energy and the AFB, but the category would most likely stay the same (from experience). Now, how much change would you tolerate? 10% Would you add 10% or so to the incident energy on the label and AFB just in case? Keep the labels as long as the category is the same?

Looking forward to the comments.

Casey


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PostPosted: Wed May 04, 2011 8:35 pm 
Sparks Level

Joined: Mon Mar 29, 2010 5:02 am
Posts: 136
You are asking if the labels that you are installing to warn someone of a hazzard(s) in an area are wrong is it acceptable? If the boundaries are incorrect and the incident energy is wrong and anything every went sideways which way would the finger point?

Plus.. If the labels and the studies are not kept up to date, there will be a potential feeling of ignorance of the labels..

That is the joy of the labels, regardless of how many there are...


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PostPosted: Thu May 05, 2011 5:52 am 
Arc Level

Joined: Wed Jun 04, 2008 9:17 am
Posts: 428
Location: Spartanburg, South Carolina
C. Harman wrote:
Hi,
I was working on arc flash labels for a wind site. We are labeling 87 turbines with possibly 20 labels per turbine, which equals a ton of labels.

You are using heavier labels than us. :D

Seriously, if you anticipate a change in fault current, use the maximum anticipated future fault current as a scenario in the current study and label accordingly if the higher current is the worst case.


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PostPosted: Thu May 05, 2011 7:52 am 

Joined: Tue Mar 02, 2010 1:50 pm
Posts: 26
The scenario I mentioned is somewhat hypothetical - there are no plans to expand that particular wind site, so there is no "future" fault current available. Before I place 2000 labels, I'd like like to know what I will do in case of something like this happening though.
I can see the issue with having significantly greater incident than is shown on the label, but are you going to relabel 87 turbines and produce 2000 labels because you are .01 cal/cm^2 off, and have maybe an addional inch in the AFB? That's ridiculous in my opinion. So does anyone have a cut off where they would relabel and where they would not? Would you multiply the values in this case by 5% or so just to make sure you're covered?

Thanks,

Casey


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PostPosted: Thu May 05, 2011 8:17 am 
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Joined: Mon Jan 18, 2010 11:35 am
Posts: 525
Location: Wisconsin
I would not include 'specific' arc flash incident energy values on my labels.
The labels are there so that proper PPE can be selected, therefore there is nothing wrong with showing 'maximum' AFIE values and boundaries based on categories, for example the label could say: Cat 1 PPE required, 4 cal/cm² incident energy, and 37" flash protection boundary.


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PostPosted: Thu May 05, 2011 8:20 am 

Joined: Tue Mar 02, 2010 1:50 pm
Posts: 26
Does anyone round up to the nearest foot or add margin on the AFB?


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PostPosted: Fri May 06, 2011 4:57 am 

Joined: Fri Sep 05, 2008 8:10 am
Posts: 36
There is nothing wrong with having PPE requirements or AFB distances over what has been calculated. If you have 87 turbines with AFB between 2'-3' perhaps make a site standard of 3' for example. It clears up alot of confusion. Same with the PPE if some require 8 cal/cm2 and some 12, then call them all 12 and be done. Just be sure you have the records to back this up. As someone said the labels do not need to be specific to each piece of equipment.


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