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 Post subject: MV Padmount Equipment
PostPosted: Wed Feb 03, 2010 12:43 pm 
Arc Level

Joined: Wed Jun 04, 2008 9:17 am
Posts: 428
Location: Spartanburg, South Carolina
What calculation method do you think would be most appropriate for medium voltage padmount equipment? IEEE 1584 or ARCPRO?

I'm of the opinion that incident energy for deadfront padmount equipment would be best calculated with ARCPRO because the probability of a three-phase fault is remote and IEEE assumes that all faults develop into three-phase faults.

ARCPRO is based on open-air faults but has a multiplier that can be applied for arc-in-a-box.

For three-phase live-front equipment, I think IEEE calcs are more appropriate because three-phase arcs can occur.

Does it make any difference if the owner is an industry or a utility? NFPA 70E is required for industry and NESC is required for utilities. NFPA has IEEE calcs in its appendix and NESC uses ARCPRO do develop tables for voltages > 1kV, but neither standard requires a particular calculation method.


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PostPosted: Wed Feb 03, 2010 1:22 pm 
Sparks Level

Joined: Sun Dec 23, 2007 1:44 pm
Posts: 348
Location: Charlotte, NC
We have used Arcpro for the dead front high voltage and 1584 for the exposed low voltage on padmounted equipment for just the reasons you stated.

One would think that with proper application either method should be suitable, but then there is the case of the engineer being found at fault for not having minimum settings on the ground fault trip. So I guess logic has no place in the courtroom.


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PostPosted: Wed Feb 03, 2010 2:08 pm 
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Joined: Tue Feb 24, 2009 7:05 am
Posts: 252
acobb wrote:
So I guess logic has no place in the courtroom.


It is logic. It's just lawyers logic, not engineers logic. See the Chewbacca defense, for an example of lawyers logic.


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PostPosted: Wed Feb 03, 2010 5:47 pm 
Sparks Level

Joined: Sun Dec 23, 2007 1:44 pm
Posts: 348
Location: Charlotte, NC
Sad but true!


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PostPosted: Thu Feb 04, 2010 7:34 am 
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Joined: Mon Jun 02, 2008 11:58 am
Posts: 1103
Location: Charlotte, NC
Vincent B. wrote:
See the Chewbacca defense, for an example of lawyers logic.


Classic, I loved that episode.


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