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 Post subject: IEEE1584 2018 model extension up to 20kV
PostPosted: Fri Feb 26, 2021 6:48 am 

Joined: Tue Mar 05, 2019 5:47 am
Posts: 10
HI

I'm working on project where we have 20kV MV ring. Part of work is arc flash study. I know that IEEE1584 -2018 official equation limit is 15kV and I suppose to use NESC or EPRI or ArcPro. I have MV switchgear so arc in box VCB configuration which is not for NESC and out of range of EPRI which are available in SKM (I still need to test it in ETAP). So long story short :
- I did hand calculation for VCB Typical, short circuit of 9kA and 500ms trip time at 14.3kV I have 5.2 cal/cm2
- I played in excel and results between 15 and 20kV are slightly different 5,08 cal/cm2
- I played with SKM tool to see difference between 10 to 15kV arc for same configuration and it is 4,97 to 5,19

Of course If I use 20kV I got values like 55 cal/cm2 which comes from switching to Lee method but I don't like it. Either NESC ( OSHA table) or EPRI are not suitable but I can't verify it with ArcPro.

Question:
1. Does anyone knows any work or paper that was looking into expanding 1584 to slightly higher voltages with reasonable error ?
2. Can you verify 20kV 9kA 500ms configuration typical for 15kV in Arc Pro for results ?


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 Post subject: Re: IEEE1584 2018 model extension up to 20kV
PostPosted: Sun Feb 28, 2021 3:21 pm 
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Location: Scottsdale, Arizona
As you found, the incident energy does vary with voltage so it voltage is important. The issue above 15 kV is that IEEE 1584 has not been validated - I can't say it is right or wrong, only that it is valid up to 15 kV.

As you saw with the Lee Equations, since they are more heavily weighted towards voltage, the result tends to be extremely large as the voltage increases.

There is informal talk of some day (no time soon) taking IEEE 1584 to higher voltages, perhaps 35 kV. However, it is just that, informal conversation of "what if". But that is how new projects begin -as informal discussions about "what if" and "some day".

Right now there are a few other items higher up on the radar screen and nothing about higher voltages. But someday....


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 Post subject: Re: IEEE1584 2018 model extension up to 20kV
PostPosted: Mon Mar 01, 2021 2:21 am 

Joined: Tue Mar 05, 2019 5:47 am
Posts: 10
Thank you Jim for update. In the meantime I played a bit with numbers with ETAP HV tool ( reverse engineering of EPRI test I believe) and It shows me in return bit higher results:

20kV 8,82kA 250ms is 2,49 (IEEE1584) vs 6,66cal/cm2 (ETAP HV)
20kV 8,82kA 100ms is 0,99 (IEEE1584) vs 2,67cal/cm2 (ETAP HV)

I played with voltage in ETAP tool and it barely has influence on results (as in IEEE1584 if I take it 1 to 1 and I didn't do any errors). What seems to be a reason for results difference is probably in ETAP "reflectivity ratio" factor which was here 2,14. I used for hand calculation VCB configuration ( due to time limits I picked only one equation 14300 VCB) which gives lower results.

Will be nice to see voltage extension of IEEE1584 up to 36kV which is product range for MV switchgears. It will make life easier.

PS. I saw somewhere a paper about expanding IEEE calculations to higher level voltages (33kV or 36kV I think ) but I can't find it. Need to dig bit more.


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 Post subject: Re: IEEE1584 2018 model extension up to 20kV
PostPosted: Mon Mar 01, 2021 7:07 am 
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rutz - I am not sure what country you are in but at that voltage, it would be considered utility like and fall under OSHA 1910.269 for arc flash. There is an Appendix E which contains info on arc flash and there is a table that lists acceptable methods to determine incident energy for various voltages. For voltages greater than 15kV, only ArcPro is listed as acceptable.

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 Post subject: Re: IEEE1584 2018 model extension up to 20kV
PostPosted: Mon Mar 01, 2021 8:00 am 

Joined: Mon Dec 03, 2018 11:09 am
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Marcia Eblen and I have a paper for the 2021 IEEE Electrical Safety Workshop [1] where we argue that the 1584-2018 models can be applied up to 35 kV. This is based on EPRI tests of medium-voltage equipment and the IEEE/NFPA data used to derive the IEEE 1584 models. We show that system voltage is not a key factor. The main factors for incident energy are the current, the duration, the electrode orientation, and the electrode gap. Physically, what's important is the arc voltage, not the system voltage. The arc voltage is mainly a function of arc length (with a modest multiplier based on arcing current). For the lengths of arcs you have in MV equipment, any medium-voltage source is stiff enough to supply that voltage. So, the results don't vary significantly with system voltage.

[1] Short, T and Eblen, M, "Comparison of IEEE 1584-2018 Predictions with Tests on Real-World Equipment," IEEE Electrical Safety Workshop, 2021. To be presented in a focus session on Wednesday, March 10, 2021. https://electricalsafetyworkshop.com/sc ... fe98a-d9dc


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 Post subject: Re: IEEE1584 2018 model extension up to 20kV
PostPosted: Mon Mar 01, 2021 8:05 am 
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ArcPRO has been verified up to 33kV. In my experience, IEEE 1584 will overpredict but the electrode configuration is VERY important to consider. Barry has a good suggestion to use the OSHA tables. Just be very careful reading those tables (like the NESC, they have caveats). We always used ArcPRO just to be professional. MV arc flash is typically overpredicted in my experience and if there is no live work.

ArcPRO 4.0 is coming soon. Pretty major update for MV equipment.

Hugh Hoagland
ArcWear, A Kinectrics Company
arcwear.com
kinectrics.com


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 Post subject: Re: IEEE1584 2018 model extension up to 20kV
PostPosted: Tue Mar 02, 2021 3:33 am 

Joined: Tue Mar 05, 2019 5:47 am
Posts: 10
tshort wrote:
Marcia Eblen and I have a paper for the 2021 IEEE Electrical Safety Workshop [1] where we argue that the 1584-2018 models can be applied up to 35 kV. This is based on EPRI tests of medium-voltage equipment and the IEEE/NFPA data used to derive the IEEE 1584 models. We show that system voltage is not a key factor. The main factors for incident energy are the current, the duration, the electrode orientation, and the electrode gap. Physically, what's important is the arc voltage, not the system voltage. The arc voltage is mainly a function of arc length (with a modest multiplier based on arcing current). For the lengths of arcs you have in MV equipment, any medium-voltage source is stiff enough to supply that voltage. So, the results don't vary significantly with system voltage.

[1] Short, T and Eblen, M, "Comparison of IEEE 1584-2018 Predictions with Tests on Real-World Equipment," IEEE Electrical Safety Workshop, 2021. To be presented in a focus session on Wednesday, March 10, 2021. https://electricalsafetyworkshop.com/sc ... fe98a-d9dc


tshort - it will be great to red it once it is available. I will keep an eye on it as it is inline what I'm looking for.

Regarding OSHA - as far I saw it OSHA clearly says it is for OPEN ARC equipment only which you see in utility business however I'm looking for up to 36kV metal enclosed switchgears like from ABB, Siemens, Eaton etc whcih are used in industry or as RMU.

> Hugh I actually never had to use Arc Pro as most of my work is not utility type but it comes more often so i need to check pricing of it.


PS. I'm from Poland :) If I didn't present myself I'm Marcin Ruta to keep it more open (you can find me on LinkedIn).


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 Post subject: Re: IEEE1584 2018 model extension up to 20kV
PostPosted: Tue Mar 02, 2021 6:25 am 
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rutz wrote:
Regarding OSHA - as far I saw it OSHA clearly says it is for OPEN ARC equipment only which you see in utility business however I'm looking for up to 36kV metal enclosed switchgears like from ABB, Siemens, Eaton etc whcih are used in industry or as RMU.


If you read the footnotes for the Appendix E, Table 3, you will see the Y for ArcPro in column for 3 phase in a box has the superscript 4. This refers to footnote 4 which states that OSHA will deem the results of this method reasonable when the employer adjusts them using the conversion factors for 3 phase arcs in open air or in an enclosure, as indicated in the program's instructions.

Note that this was written when the original ArcPro was in use and you hand manually do the conversion and the latest version has a drop down box where you pick the type of arc and the adjustment is done in the program.

So, if you looking for a value that you can use in your safety program and have a basis for the result, you would be in a much better legal position if something happened than if you used a method that may be harder to justify in a legal setting. Just saying.

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 Post subject: Re: IEEE1584 2018 model extension up to 20kV
PostPosted: Thu Mar 04, 2021 1:58 am 

Joined: Tue Mar 05, 2019 5:47 am
Posts: 10
thanks wbd I will look into it one more time. From legal perspective I'm in EU but what you wrote sounds reasonable also.


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 Post subject: Re: IEEE1584 2018 model extension up to 20kV
PostPosted: Mon Mar 15, 2021 6:45 am 

Joined: Mon Dec 03, 2018 11:09 am
Posts: 8
tshort wrote:
Marcia Eblen and I have a paper for the 2021 IEEE Electrical Safety Workshop [1] where we argue that the 1584-2018 models can be applied up to 35 kV. This is based on EPRI tests of medium-voltage equipment and the IEEE/NFPA data used to derive the IEEE 1584 models. We show that system voltage is not a key factor. The main factors for incident energy are the current, the duration, the electrode orientation, and the electrode gap. Physically, what's important is the arc voltage, not the system voltage. The arc voltage is mainly a function of arc length (with a modest multiplier based on arcing current). For the lengths of arcs you have in MV equipment, any medium-voltage source is stiff enough to supply that voltage. So, the results don't vary significantly with system voltage.

[1] Short, T and Eblen, M, "Comparison of IEEE 1584-2018 Predictions with Tests on Real-World Equipment," IEEE Electrical Safety Workshop, 2021. To be presented in a focus session on Wednesday, March 10, 2021. https://electricalsafetyworkshop.com/sc ... fe98a-d9dc


The submission version of this paper is now available at: https://distributionhandbook.com/papers ... s_2021.pdf


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