Jean-Francois Ouellet wrote:

Here is the quiz:

The IEEE 1584 standard is fairly explicit on the limitations of its incident energy calculation model.

If I use the formula to find the arcing current of a system under 1000V (P.10 Std 1584-2002) I cannot go under a bolted fault current of 700A.

Is that mean that in my system, at 600VAC and a bolted fault current of only 0.200kA, there is no arc that can be sustained? I doubt so. I am pretty sure there is enough energy there to sustain an arc.

Is there an other model for a bolted fault current under 700A?

Or should I consider that no arc would be sustained at that low current?

The 700 Amps (and 106 kA) are just the ranges where the model is considered valid. Outside those ranges, who knows. So to answer your question, I see two options:

1) Default to the theoretical Lee equation

2) Use the IEEE 1584 model recognizing that it is outside the range of validity.

Neither option is a good one but those are the only options available. I'm sure you will find the incident energy will be minimal.

I'm don't know if you can sustain an arc at 200 amps easily at 600V however, given the right conditions, anything is possible.