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 Post subject: 15kV Deadfront Switchgear - Single or Three Phase?
PostPosted: Wed Oct 30, 2019 12:57 pm 

Joined: Wed Oct 30, 2019 11:11 am
Posts: 2
Hello All,

I am performing an arc flash study on a 15kV utility distribution system and would like to hear thoughts on what configuration a 15kV deadfront switch would qualify as?

(https://www.eaton.com/us/en-us/catalog/medium-voltage-power-distribution-control-systems/pad-mounted-most-oil-switch.html)

I understand using 1584 it would be Horizontal Enclosed but could the case be made that a fault would result in a single phase to ground and use ArcPro for the analysis?

Thanks,
Ozro


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 Post subject: Re: 15kV Deadfront Switchgear - Single or Three Phase?
PostPosted: Mon Nov 04, 2019 7:12 am 
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Joined: Wed Jun 04, 2008 9:17 am
Posts: 428
Location: Spartanburg, South Carolina
I would use ArcPro. There will be no 3Ø faults on deadfront equipment.


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 Post subject: Re: 15kV Deadfront Switchgear - Single or Three Phase?
PostPosted: Mon Nov 25, 2019 9:24 am 
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Joined: Tue Oct 26, 2010 5:00 pm
Posts: 187
Location: Maple Valley, WA.
Per OSHA, they do not recommend the use ArcPro for enclosed 15 kV switchgear

See 1910.269 - TABLE 3—Selecting a Reasonable Incident-Energy Calculation Method


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Robert Fuhr, P.E.; P.Eng.
PowerStudies


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 Post subject: Re: 15kV Deadfront Switchgear - Single or Three Phase?
PostPosted: Tue Dec 03, 2019 2:29 pm 

Joined: Wed Oct 30, 2019 11:11 am
Posts: 2
Thank you both for your replies.

Robert, I was planning to use ArcPro only if the justification could be made that three phase arcs were not likely to occur in deadfront SWGR. If I am reading that table correctly, OSHA accepts using ArcPro for single phase calculations at 15kV.


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 Post subject: Re: 15kV Deadfront Switchgear - Single or Three Phase?
PostPosted: Tue Dec 03, 2019 2:42 pm 
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Joined: Tue Oct 26, 2010 5:00 pm
Posts: 187
Location: Maple Valley, WA.
Ozro wrote:
Thank you both for your replies.

Robert, I was planning to use ArcPro only if the justification could be made that three phase arcs were not likely to occur in deadfront SWGR. If I am reading that table correctly, OSHA accepts using ArcPro for single phase calculations at 15kV.


OSHA requires that you use 3 Phase bolted faults for enclosed equipment. They allow you to use ArcPro (using line to ground fault current) and then use "with multipliers" to increase the AF energy to a supposedly equivalent 3 phase value. I have done a lot of research and contacted many other engineers and nobody seems to know what the multipliers should be.

On 208 to 15 kV systems, I would recommend using IEEE-1584-2018 to determine the AF energy and boundaries for both open and enclosed equipment.

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 Post subject: Re: 15kV Deadfront Switchgear - Single or Three Phase?
PostPosted: Wed Dec 04, 2019 9:35 am 
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Joined: Tue Jan 13, 2009 5:00 pm
Posts: 532
Quote:
I have done a lot of research and contacted many other engineers and nobody seems to know what the multipliers should be.


In ArcPro 3.0, just choose your fault type from the drop down. 3 phase AC enclosed is one of several choices. In 2.0, the factors are listed in the help file. Unfortunately, the range is large for some.

1 phase in a box 1.5
3 phase 1.2 to 2.2
3 phase in a box 3.7 to 6.5.


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 Post subject: Re: 15kV Deadfront Switchgear - Single or Three Phase?
PostPosted: Wed Jan 29, 2020 10:26 am 

Joined: Mon Jun 05, 2017 8:07 pm
Posts: 13
The ability to use multiple scenarios in a given model is the key here. ETAP software has Arcfault module similar to arc pro that calculated Phase to Ground or 3-Phase arcs on 15kV or above, The key to the calculations is not the voltage but the gap between the conductors.

The user can able to create multiple scenarios under a single system project and account for different inputs to obtain the realistic incident energy results. Also the flexibility of the ETAP configurations, annotations in the one line is far more convenient to analyze the results . In addition, there is a stand alone ETAP calculator introduced in 19.0 version that calculates quick results based on multiple inputs to start the analysis process by avoiding odd inputs in the program

The arc fault method in ETAP is based on comprehensive set of tests and experiments done by EPRI (Electrical Power Research Institute) which led to the development of empirical equations.

The details of this method is summarized in the paper below from ESW 2019

"High Voltage Arc Flash Assessment and Applications", Paper no. ESW2019-38

Thank you
Regards
Raghu


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