Hello Jim,

Thanks a lot for your answer.

It's now quite clear and consistent.

We'll be able to finalize our arc flash calculation module in our software.

Best regards

Philippe Aupetit

Trace Software International

Great! Glad to help. Check back here if you have any other questions.

Statistics: Posted by Jim Phillips (brainfiller) — Tue Feb 02, 2021 9:39 am

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It's now quite clear and consistent.

We'll be able to finalize our arc flash calculation module in our software.

Best regards

Philippe Aupetit

Trace Software International

Statistics: Posted by Ph. Aupetit — Tue Feb 02, 2021 4:14 am

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After discussing this with various people, the reference to the examples in Annex D that use Iarc-min in the numerator of equations D53, D55 and D57 should be Iarc without the “min” This is consistent with the equations in Clause 4 of the body of 2018 IEEE 1584.

Have a great day!

Statistics: Posted by Jim Phillips (brainfiller) — Sat Jan 30, 2021 10:20 am

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Thank you very much for your involvement.

Best regards

Philippe

Statistics: Posted by Ph. Aupetit — Thu Jan 28, 2021 7:25 am

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Statistics: Posted by Ph. Aupetit — Tue Dec 22, 2020 10:23 am

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No comment on my previous post ???

I've been digging into this and have several people involved. We should have a response after the holidays since most are winding down now (me included). Happy Holidays.

Statistics: Posted by Jim Phillips (brainfiller) — Tue Dec 22, 2020 10:18 am

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I understood the need to use Iarc600 in the numerator for the calculation of IE and AFD for both the 100% arcing current and the reduced arcing current when Voc ≤ 600 V.

But this leads me to ask another question:

Why use, as in the D1 example, the currents Iarc_600/2700/14300_min in this same numerator for the calculation of IE and AFD with the reduced arcing current?

Let's take an example:

Let's use the same system as in the D2 example but with a Voc=600 V. For the reduced arcing current (28.65 kA), with the equations D101 and D104 we find (keeping T=319 ms) IE=14.34 cal/cm2 and AFB=2879 mm.

Let's repeat the same example with a Voc=601 V. The equations D53, D55, D57 of the D1 example must then be used. It is then found (keeping T=319 ms) Iarc_min=28.66 kA, IE=9.95 cal/cm2 and AFB=2290 mm.

So for a Voc variation of 1 V, IE drops 30% and AFB drops 20% which does not seem to me very consistent.

If we replace in the equations D53, D55, D57 the numerator values Iarc_600/2700/14300_min per Iarc_600/2700/14300, then we get the following results: Iarc_min=28.66 kA, IE=14.35 cal/cm2 and AFB=2880 mm, which is more consistent.

On the other hand, if we redo the D1 example by replacing the numerator value Iarc_600/2700/14300_min by Iarc_600/2700/14300 for equations D53, D55, D57 the results become IE=3.21 cal/cm2 (instead of 3.19) and AFB=1712 mm (instead of 1704). The difference is small, which is normal since the influence of the reduced arcing current decreases as the voltage increases.

It should also be noted that the Excel calculator available on the "https://ieee-dataport.org/open-access/arc-flash-ie-and-iarc-calculators" website uses the numerator value Iarc_600/2700/14300 for the equations D53, D55, D57.

Do you not think that a clarification would be useful on this problem? This may be important in Europe where 690V voltage is commonly used in industrial facilities and where the use of the numerator value Iarc_600/2700/14300_min in equations D53, D55, D57 could lead to calculated values of IE and AFB underestimated in relation to reality.

At your disposal to discuss it more precisely if necessary.

Regards

Philippe

Statistics: Posted by Ph. Aupetit — Tue Dec 01, 2020 4:09 am

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The adjustment to the specific voltage is accounted for with Iarc for 100% and Iarc_min for minimum. Where both are at the specific nominal voltage (Voc)

This is quite different than the medium voltage solution where you calculated everything at two voltages (often 2.7 and 14.3 kV) and interpolate between the two values.

Statistics: Posted by Jim Phillips (brainfiller) — Sun Nov 29, 2020 4:27 pm

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I am developing an arc flash calculator and I have the same question as Balaji:

Why in equation D101, "k3*Iarc_600" is used in place of "k3*Iarc_600_min" which is not complying with the title of Step 10 "Repeat Step 4 using the

Thanks for your answer.

Regards

Philippe Aupetit

Statistics: Posted by Ph. Aupetit — Thu Nov 26, 2020 3:34 am

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Wound rotor induction motors have an external circuit coming from the motor rotor, through slip rings, to a variable resistor bank. The slip ring enclosure and the resistor bank cabinet have an arc flash risk. Is there an established method/standard for calculating the incident energy along the motor secondary circuit? Have you ever run into the situation before?

I do not have any experience with wound rotor induction motors.

Any one cares to enlighten me? Thanks.

Statistics: Posted by RECS — Thu Aug 13, 2020 11:35 am

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Hi Jim: Does the IEEE 1584 committee have any plans for higher voltage overhead lines? Like Arc Pro?

Thanks for all you do!

There has been some discussion about extending to the 35-38 kV range for equipment but it is just an informal discussion. So nothing anytime soon. There is nothing about higher voltage overhead lines. Too much left to do at lower voltages first.

Statistics: Posted by Jim Phillips (brainfiller) — Tue Aug 11, 2020 9:26 am

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Statistics: Posted by K. Engholm — Mon Aug 10, 2020 11:18 am

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My understanding is that the first priority will probably be some DC content.

My personal desire would be acquiring data at higher fault current values, hopefully all the way to 200kA.

Both of these type of projects require testing few laboratories can provide and have significant cost associated. As Jim stated, this is expensive and funds are limited.

BUT keep your cards and letters coming to whoever you know in the IEEE working group. It is important that whatever expansion is undertaken it addresses real needs in the industry.

Yes DC is high on the list. I have been pushing DC for years and a while ago it up on the radar screen. Single phase is also on the list as mentioned. Going to 200 kA will be quite difficult due to lab constraints. We were limited this time around. As I understand, one of the labs had some damage at higher currents and throttled the upper current capabilities back. It is also expensive as we all know. Stay tuned, it all moves slow but it is moving in the right direction!

Statistics: Posted by Jim Phillips (brainfiller) — Mon Aug 10, 2020 7:55 am

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My personal desire would be acquiring data at higher fault current values, hopefully all the way to 200kA.

Both of these type of projects require testing few laboratories can provide and have significant cost associated. As Jim stated, this is expensive and funds are limited.

BUT keep your cards and letters coming to whoever you know in the IEEE working group. It is important that whatever expansion is undertaken it addresses real needs in the industry.

Statistics: Posted by Electricidad — Mon Aug 10, 2020 7:47 am

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