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EddyWilbelstrom, I run your case scenario using ARCAD's web app and the results are in agreement with your findings. Namely, 1.2 cal/cm2 @ 2524 mm distance and 11.7 cal/cm2 @610 mm distance:

You may want also consider double line to ground. In this example, it will be even higher than line to ground. Check http://www.arcadvisor.com/example_2.html and http://www.arcadvisor.com/faq/mva_to_ka.html on how to resolve unsymmetrical faults using MVA method for short circuit analysis.

I've put together quick arc blast TNT equivalent calculator for those who'd be interested in arc blast explosive effect. You can find it in http://www.arcadvisor.com/faq/arc_blast_tnt_equivalent.html

123MB, take it one step further and analyse arcing power and arcing current as a function of source x/r. Your finding might shatter common sence stand point again;).

thanks,ijl for making the calculations and confirming my findings. As amazing as it is, theory reveals things that are not very obvious from common sense point of view.

Skogsgurra, I think I agree with you. My observations are that maximum active power dissipation in arc occurs when arc resistance matches the source impedance

I've done power flow analysis and the results show that this statement is just not true. Did you try to do the analysis?

Going through old posts related to arc flash, I came across thread238-161138 a statement that If fault arcs are assumed to be resistive then the maximum power occurs when the arc resistance matches the source resistance. How about purely inductive source? Here, arcing resistance would have to be...

How accurate is an assumption of resistive nature of an arc? Is there any model that allows to calculate arc reactance?

I've come up with online arc blast initial pressure calculator. You can find it at http://www.arcadvisor.com/faq/arcblast.html Feel free to give it a try.

dpc, you are absolutely right, the things that bothers me is that in your example the energy would be proportional to Iarc^2, not to Iarc alone as in Ralph Lee's equation. This is empirical formula and I would have more confidence if I knew the voltage range they used to take pressure...

My opinion is the higher the system voltage the higher voltage drop in the supply network AND gap between conductors. Hence, higher voltage produces higher arcing current (consider IEEE 1584 formula for arcing current). Thermal effect and heat rise are proportional to product of current and...

So, would the pressure effect of say 208V 100kA arc be equivalent to 5kV 100ka arc, for example? Hard to believe.

I am trying to calculate pressures developed by electrical fault. I 've come across formula published in http://ecmweb.com/mag/electric_putting_arcflash_calculations/ from Ralph Lee's paper, "Pressures Developed by Arcs": Pounds/ft^2=(11.5×kA arc)÷(distance from arc in feet)^0.9 There are also...

Check http://www.arcadvisor.com/faq/dc_direct_current_arc.html

The Moon Yuen article mentioned by rcwilson can be downloaded from http://www.arcadvisor.com/pdf/ShortCircuitABC.pdf

Isc = Vs / Ri - Short circuit current as a function of source voltage and internal resistance Iar = (Vs - Var) / V * Isc - Arcing current as s function of short circuit current and arcing voltage, where, Var = Uc + Upc * L, Uc is the sum of the anodic and cathodic drops, It has been found to...

Check short circuit online calculator at www.arcadvisor.com It features input data analysis and hard coded error propagation rules ensuring that the resulting fault current values are not more precise than justified by the accuracy of input data including X/R.

Fuse literature shows pre-arcing (melting) and clearing i2t. I have never seen fuse specs showing actual fuse -pre-arcing- and clearing time. Also, I wouldn't calculate fuse operation time based on i2t value and prospective fault current value. i2t is test value, for specific test setup...

current inside capacitor bank doesnt depend on reactor size, and equals 384,000kVAR / 1.73 / 230 = 960A. The reactor size affects total current fed to the capacitor|reactor assembly.