if anyone can answer those questions, i would be appreciate
Your questions have very complex answers, to fully answer them would take 122 pages (A.k.a IEEE-1584). If this is not homework what is it? Please don't say you are conducting an arc flash analysis.
I will give you some very basic answers to get you on the correct path.
q1) before arc flash analysis, i do short circuit analysis to calculate fault current for every bus. this fault current is the same current as bolted fault current?
available fault current:
The electrical current that can be provided by the serving utility and facility owned electrical generating devices and large electric motors, considering the amount of impedance in the current path.
bolted fault current:
A short circuit or electrical contact between two conductors at different potentials in which the impedance or resistance between the conductors is essentially zero.
q2)what are diffrences between arc current and bolted fault current?
Arcing current includes the impedance of the arc, this is different for different voltages, your highest possible and lowest possible arcing currents must be calculated and the clearing times determined for your Ei calc, at a minimum, usually many different points would be used.
q3)what is the gap between conductors? is it effect the arc current?
Depends on the class and type of equipment, yes it has a major effect on arcing current.
q4) having open cofiguration or box configuration effects arc current?
No, but it has a huge effect on incident energy
q5)what is the usage of protective device coordination before arc flash analysis?
To ensure you have selective coordination in your system.
q6)to calculate incident energy, what is the effect of arcing time?
Perhaps the largest variable, which is why you often see higher incident energies with your lower arcing current calculations (And why reducing available fault current can increase arc flash hazards, perhaps the most misapplied mitigation method out there)
this arcing time inside the formula comes from protective device coordination?
No, it comes from seeing what your clearing time would be for your different arcing currents calculated would be on the OCPD's time current curve. And this is also the fatal (no pun intended) flaw in the arc flash analysis process, you are ASSUMING the OCPD will actual trip where the TCC says it will, a recent study by NETA on over 340,000 protective devices showed23% of the breakers tested failed to operate within the published TCC's. (And over 10.5% failed to operate at all).
